It looks like you're new here. If you want to get involved, click one of these buttons!
It's hard to make a good MMORPG. But it can be different types of hard depending on what you're trying to do.
Let's take an analogy. It's hard to walk ten thousand miles. It's also hard to run a 100 meter dash in under 11 seconds. But they're very different types of hard.
Most humans could walk ten thousand miles if so inclined... eventually. If they started on the project at a young enough age. At three miles per day, it would take you about nine years. That's doable. Most humans, on the other hand, could never run a 100 meter dash in under 11 seconds. It takes considerable physical prowess to do that.
On the other hand, for those few people who can run a 100 meter dash in under 11 seconds, it doesn't take very long to do so. Some of them could do it hundreds of times if so inclined. Not all, of course; if your personal best is 10.99 seconds, it's hard to replicate that a hundred times. But world-class sprinters that can push 10 seconds don't have to run full throttle to break 11.
Meanwhile, no one can run ten thousand miles a hundred separate times in a lifetime. At a full marathon per day, that would take over 100 years. I don't know if elite endurance athletes would be able to walk 26 miles per day many days in a row, but even if they could, no one stays in the peak physical condition necessary for that for 100 years. The problem is that walking ten thousand miles just once takes too long.
So what does this have to do with MMORPGs? Making a good theme park game is largely about making lots of content. That's not all that there is to it, of course, but it's a big chunk of it. You make lots of races, lots of classes, lots of quests, lots of world zones, lots of loot drops, lots of NPCs, and so forth, with every single one hand-done.
Making one quest or one NPC or one loot item isn't hard. Lots of people can do it, so it's not the second type of hard. But it is the first type of hard: it takes time to make each one. You can't make a good theme park game on a smalll budget. You can't even make a mediocre theme park game on too small of a budget. But if you throw enough money at a theme park, you can finish it and it will more or less work. It might not be great, but it probably won't be abysmal, either.
Sandbox games are different. To make a good sandbox game, you have to have a number of complicated game mechanics that work together in complex ways. And they need to work together very, very well. You need for interesting gameplay decisions to arise in very complicated ways--and for players to not have a single way to short-circuit the intended complexity.
That is the second type of hard discussed above. Most game programmers can't do it. They could try, but the game would probably be a train wreck.
However, a sandbox game isn't the first type of hard. You don't need hundreds of custom-done quests, and hundreds of custom-done mobs, and so forth to make a good sandbox game. The game will succeed or fail on the basis of whether your sandbox mechanics make for interesting gameplay.
Suppose that you're in charge of choosing an MMORPG to be made and need to decide whether you want to make a theme park game or a sandbox. And let's suppose that you've got a big budget. Which do you choose? If you say "sandbox because I like sandboxes", then that's why you're not given that decision to make.
If you try to make a theme park game, you'll end up with a game that more or less works. You might end up losing money on the game, but you'll at least deliver a working theme park game. Throwing enough money at the problem nearly guarantees that.
But what about a sandbox game? A sandbox game doesn't have tons of custom-done content that will take players tens or hundreds of hours to play through. If the sandbox mechanics work well, then great, you'll have a huge hit on your hands. But if they don't? If you don't have the programmers on staff to make sandbox mechanics work well, you'll have a spectacular failure on your hands. That's embarrassing, and not beneficial to your future employment. And how do you know if your programmers can deliver a good sandbox? The only way to find out is to let them try.
Now suppose that you have a small budget. Now a theme park isn't really an option. You can try to make a theme park, and make quests and dungeons and loot drops and so forth and hold players' hands as they go through your content. But someone else with a bigger budget can do everything you can do, and do ten times as much of it. You can't really make up for your lack of quantity with superior quality, either. Not only are you constrained from the start on your budget with resources spread thin, but in theme parks, quantity has a quality all its own.
A sandbox, on the other hand, is doable. You don't need to make thousands of custom items. You make a relative handful of base items, and then let the stats vary depending on a variety of things. You don't need to make hundreds of custom mobs. You can get by with dozens, plus some copies and some randomness, so long as you make them adequately interesting. And so forth.
So on a small budget, what do you make? Even if you're a theme park fan, budget realities are going to force you to at least include some elements that people would think of as being sandbox.
Let's look at this another way. Suppose that you're going to make a sandbox game, and are deciding on how big of a budget to give it. There's always stuff that you can do with a larger budget that you can't do with a smaller budget. But while theme parks get vastly better as you throw more money at them, sandboxes only get a little better. If you don't have programmers who can do sandbox mechanics well, your game is going to be a failure, and you'd much prefer a small failure to a large one.
Even if you could make a successful sandbox game on a small budget, it doesn't follow that you could do the same on a large budget. Whether a game is commercially successful depends not just on revenue, but also expenses. For example, SWTOR is probably a commercial failure. It certainly is one if the rumored $300 million budget is anywhere near accurate, though that number includes the cost of EA buying BioWare for the express purpose of making SWTOR.
On the other hand, if SWTOR had exactly the same sales figures on a $10 million budget, that would be a smashing success. EA earned several times that on initial box sales in the first month after launch alone. Anything else after that would just be gravy.
Throwing more money at your game won't be the difference between the game being good or not. But it will make a huge difference in how high of a sales threshold you need to clear for the game to be a commercial success. Do you really want a larger budget than necessary to make your sandbox game? Really?
When you first start on the project, no, you don't. It might be nice to have some extra money available for when things go over budget, but you don't spend it if you don't have to. Maybe if it's clear that the game is going to be something special, you can increase the budget later. Blizzard has probably spent a lot more on developing WoW than they expected to when they first started the project. A sandbox game with WoW's level of commercial success would probably end up getting a huge budget to try to sustain that success. But even among theme parks, there is only one WoW.