So in games today, and I'll use EQ2 as my example because I've played it the most. You level up to max level as quickly as possible. We do this to get the best gear so defeating mobs will be easier.
However, when we do this the rest of the game becomes obsolete. And people rush through a game just to the end, or the highest levels a quickly as possible and designers and developers can't keep up.
Instead of doing a game, level 1-50, and then taking a year to two to release an exp pack of 50-60 so on and so forth, why not develop to game so you can't beat certain mobs without having attended certain criteria.
Again, going back to EQ2, in the exp pack that had level 80-90 crit chance was king. If you didn't have 1000% crit chance you wouldn't hit a mob. In the exp pack that was level 90-100 resolve was all that mattered. This got me thinking.
Why not do stuff like that earlier in the game. Level 30-40, 40-50, 50-60 etc. And then, to make older content not obsolete, even if you were level 60 fighting level 40 stuff if you didn't have the right stats you wouldn't defeat mobs.
Zones for level 40-50 require crit chance of 400-600%, gear dropped from those zones had super high crit chance on it, and only the epic mobs at level 50 dropped what was needed to start defeating level 51 mobs of the next zones. Which was resolve, or something. Then as you progress through lvl 51-60 you earn resolve gear which is needed to defeated the hardest level 60 mobs which dropped gear needed for the next set of levels....so on and so forth. Then you wouldn't need exp packs all the time, you'd just need to progress in levels, but also you'd need to defeat the best mobs of that level set and regardless if you were level 80, you'd still struggle with level 60 mobs unless you had earned that gear.
Anyway, it's more in depth than that, but I'm hungry and dinners ready.