I'm working my way towards a post about achievements, as requested in the open Sunday thread, but before I get there I'd like to discuss something which touches on both achievements and other sorts of rewards: What exactly does a player have to do to "achieve" something or "deserve" a reward?
Many people like to pretend that rewards and achievements are given out for "skill". But if we are brutally honest, we have to admit that this isn't the case most of the time. It takes only negligible amounts of skill to level to 80, catch 1,000 fish, collect 50 non-combat pets, or become exalted with 40 factions. You can even get a complete set of PvE or PvP epics with very little skill, if only you can find a powerful group of people you can leech from. If that requires "skill", then its more social skills than gaming skills. If you happen to have gaming skills, it helps, and might get you the reward or achievement faster, but it isn't absolutely necessary, except in very rare cases.
So what exactly do most MMORPGs hand out rewards for? Most of them reward you for time spent in game, doing some reward-related activity. Farming and grinding will get you nearly anywhere. In PvP only some arena rewards are out of reach for the unskilled, most of the PvP epics can be obtained by simply doing PvP long enough, win or lose. Many achievements are extremely grindy. And of course you gain levels and xp by doing hundreds of hours of killing monsters and doing quests, for which you need only very basic skills. Ixobelle even proposed to simply hand out a fixed amount of xp per hour, so people wouldn't have to look for the best way to gain xp, and simply do whatever was most fun for them. Unfortunately that wouldn't work, most people simply would log on, alt-tab out, and play another game in the background until they reach the level cap.
An alternative to rewarding time spent in game is to reward real time, time you pay subscription for. World of Warcraft already does that with daily quests, crafting recipes with long cooldowns, or achievements it takes a full year to complete. You often have to do a lot less for these rewards and achievements, but you can't get them without paying for the game every month. The most extreme case is EVE Online, where you earn skill points based on real time, which leads to some people basically playing EVE Offline.
The last thing MMORPGs often reward is just plain luck. Kill a random mob, and find a bind-on-equip epic worth thousands of gold. Be the only paladin in your raid, and see half of the epics dropping being plate with spellpower. Walk around a corner a see a rare named you need to kill for an achievement. But of course luck is also somewhat related to time: The more often you do something, the higher the overall chance that one day you'll get lucky.
Of course there is a good reason why most rewards and achievements in MMORPGs are related to time: The game company wants your subscription money. If you could get all the best rewards and achievements in a month or two, you would be less motivated to pay them for years. And in a way that is a win-win deal, because you of course are interested to get many hours of entertainment. But it wouldn't hurt if there were more rewards and achievements in the games that actually required more gaming skills, and not just grinding.