Gevlon weighs in on the apparent trend away from RNG-based loot tables. He looks at the loot tables and concludes that a completely ungeared level 80 resto druid in WoW entering the heroic 5-man Nexus dungeon for the first time can expect, on average, 1.6 gear upgrades per run. The number includes gear that is more suited for DPS casters than healers, but Gevlon suggests that the deficit there can be made up via skill. Fair enough.
Then Gevlon says that there are 17 gear slots on a WoW character, and, at 1.6 gear upgrades per run, a new player can expect to be outfitted in "best in slot ilvl 200" gear in only 11 runs (17/1.6). It apparently wasn't Gevlon's best math day, as he also states that there were 11 5-man dungeons at Wrath's launch, when it was actually 12. The bigger issue with the analysis is that the 1.6 gear upgrades per run number is not a constant.
If Gevlon's hypothetical new druid gets that best-in-slot healing mace on her first run, any subsequent healing weapon drops aren't all that useful for her. Alternately, a future run might allow the druid to replace a DPS-focused item with a healing-focused item as one of it's 1-2 useful drops for the druid, but that retroactively diminishes the value of the previous run. Either way, the frequency and magnitude of the upgrades drops as the player completes more dungeons.
This is a moot point if you're in Gevlon's position, capable of literally buying a whole guild's worth of alts past a bit over an entire tier of content. For them, 5-man content is a mere waystation on the way to bigger and better challenges, which they are more than able to overcome even without all of the best gear. If, on the other hand, you play in 1-2 hour chunks on no fixed schedule, and therefore cannot raid any higher content, the diminishing reward curve on the random 5-man loot table becomes an issue. That is where Blizzard, Turbine, Mythic and SOE see a role for loot tokens.
How many mounts do you need?
Though dungeon drops can be the most prominent example - my first trip through Heroic TOC got me an upgrade and a side grade, but I haven't won any useful loot in 3 runs since - this problem is not unique to gear.
Let's say that you're hoping to get players to collect more mounts - Massively reports that Turbine may be going in that direction with LOTRO. Sure, they can tell me that my horse won't follow me into Moria and try to sell me a goat. I'll probably purchase one, if for no other reason than variety.
The thing is, like gear, I can only use one mount at any given time. If they're planning on saying that Moria goats are too scared to go into Mirkwood, that's where I'm probably going to draw the line on LOTRO mounts. If they don't, what is the benefit to me of doing any work whatsoever for additional mounts?
Cosmetics? Perhaps, if the amount of work is reasonable. But appearence too has diminishing returns in that there are only so many different colors that you can slap on a horse.
Faster speed? You can go that route - I suspect that Runes of Magic will have to since selling mounts is one of their main revenue streams - but that has its drawbacks too in that it renders the slower mounts obsolete. I have a number of cool-looking WoW mounts that I never use because they're the non-epic slower versions. Ironically, that 310% holiday proto-drake would actually relegate the dozens of existing mounts I have to the slow lane. It's best not to have your new timesink remove all of the player's incentive to continue working on your older timesinks, if your goal is to sink as much of the player's time as they're willing to.
A universal problem
Other rewards are similarly affected. I'm up to 72 minipets in WoW - I'll do the Shattrath daily fishing quest when it happens to be "free baby crocolisk for fishing in Stormwind" day (it appears to be a 100% drop now until you've collected all four, where it was previously pretty rare), but I'm not spending thousands of gold or grinding out factions just for a minipet anymore.
Cosmetic outfits in games that offer them (EQ2, LOTRO)? Well, having more outfits is kind of cool, but you've only got so many slots for them, and you have to store the items you're not wearing. Titles are in the same boat - I have over a dozen of them and have worn maybe two in my WoW career. You can offer the occasional rare unique reward, like the Squire from the Argent Tournament with remote bank access, but there's a limit to how many of those you can add before they too cease to be unique.
Exploring New Worlds
Even though we do completely different things in game, Gevlon and I share a common motivation - experiencing new content. He spends time posting hundreds of glyphs on the auction house to finance his raiding habit. I roll up alts (in WoW and other games), while I do dailies and 5-mans on my main so that I'll be geared well enough to break 3K DPS on the rare occasion when I'm able to sneak into a guild raid that's short a player. That's a problem for the developers, because new content takes time. Slapping a recolored mount or vanity pet onto the end of a faction grind, a token system, or a RNG drop table is quick and easy.
The problem is that, for them and for us, these activities suffer from diminishing returns. The more mounts and pets that Blizzard adds, the easier it gets to cherry pick out the easiest ones and get to the best rewards (ironically, additional mounts and pets). My solution to this is to simply hop games when I run out of things that I consider fun to do, but that's obviously not the route that the developers would like me to take. It'll be interesting to see whether the current or future generations of games can come up with better solutions.