Top part is about how I've formed my bottom part opinions.
So I've been playing AlterAeon, a nice little MUD with an awesome class building system. Essentially the classes are best seen as archtypes that you use experience to buy into, Your first class has the base exp level then each class after has a harder experience curve. The system is set up so that you are completely and utterly expected, and need to level pretty much all the classes given time (even if you only level them to get ability points). Further more when you do level any class you get 5 'practices'/ability points that you need to choose to spend between character skills or characteristics like strength/con.
So pretty much it's class building. Or something pathfinder like with multi classing required. And pretty old school RPG in the sense that you can really screw up your character.
In my case I've primarily been playing a Thief/Druid build. Thief getting some sneak abilities that actually work, brew poisons, and a few "dagger" weapon abilities (at least that's what I'm using it for. I've ignored its social skills in favor of the crafting one). Using the Druid for some defensive abilities, then the best gathering skills in the game, and finally it's crafting abilities Brew Tincture/Salve (which is essentially the stat buffing side of potions), and rune crafting (the easiest armor enchanting, at the cost of being random) (ignoring many of the druids casting skills, and summoning skills).
When it comes to gameplay since crafting IS a class feature it means you actually get pretty good experience for it (a little less than monster bashing). With the thief's sneak abilities it lets me get into areas at higher difficulty than I'm rated for, for some nail biting gathering. Then crafting up both poisons and stat buffing tictures/salves. When it comes to fighting mosters my level unbuffed it's a pretty slow slog, in some cases with me doing multiple retreat and heals. When it comes to fighting with no holds barred with me poisoning the enemy (consumables), getting a buff or 3 on myself (consumable again), and similar: It comes to my character just plain beating down the enemy, Skill synergies on the thief side of poisons to defeat enemy regen and bleeding effects combines with druid's defensive abilities with the crafted stats of someone 3 to 5 levels higher than me is pretty awesome (It's fun beating something with difficulty rating of 3 and a description of "are you mad").
By no means an optimal build, but one that offers some varied gameplay. Most of the time you'll be a bit weaker than a normal player, but when you see a challenge you want to take you're going to win given enough prep (Worth mentioning that the poisons I make you would buy from an NPC for around 200 gold, and the buffs would buy at around 300. a lucky monster drop would be worth about 30 gold and ATM I have around 9K in the bank. Selling to NPCs is rare in the game).
Some really cool combos I've worked with: poison/bleed so that enemy can't heal through the DOT, regenertion/venomstop so that enemy dots can't affect my bonus regen, trollblut(+str, +con)/Enhance (+healt/mana/staminia)/stoneskin(def) to just hulk out.
Also worth mentioning that my class combo of Thief/Druid is listed as "Thief druids are very rare" in help files (So bonus snowflake points for me). With most people expecting you to go Thief/Warrior or Warrior/Thief for the strong synergies between the two.
After playing that much time on the character, I've actually formed a pretty strong opinion that games haven't really looked deep enough into ammo (or consumable) systems in general. And in cases where they actually do have pretty developed ones, the games haven't really taught players very well when you should actually use a consumable. For instance in something like the Witcher players are more likely to just reload a few times, then to think about which consumable they should use to get the challenge done in less total time (even though they'll be sitting there forever and never used).
Also worth mentioning that being a consumable class I've probably played longer than I would have if I went with a more optimal combat class. I can choose between doing something chill like gathering at my level, play a stealth game by gathering in higher level areas, then do something very "thinky" sitting in town analyzing my crafting options (different buffs and poisons compete for the same components), then when it comes to combat I get to choose between fighting at my level slowly working through consumables, or consuming stuff faster to work right against the experience/kill cap. I've also spent more time than normal getting into hidden areas and finding resource rich semi-secrets (something that MUDs actually pretty good at allowing builders to do).
In something like a FPS I guess properly balancing a strong ammo/consumable system would be pretty bad. Probably also pretty bad in a game with a strong PvP focus. But when it comes to actual full on RPGs, we really need more consumable systems, and for them to be pretty darn strong.
Practice doesn't make perfect, practice makes permanent.
"At one point technology meant making tech that could get to the moon, now it means making tech that could get you a taxi."