Warhammer Online recently released the 1.4 version and, along with it, two "add-on packs". These are interesting because they don't expand the game in the traditional way, but at least one of them has a profound impact on the game.
The less important pack is a "personality pack" that gives players access to new dyes, exclusive vanity pets, appearance-modification tokens, and fancy-looking mounts. The mount is if interest because, although it shares the same stats as the mounts purchasable in-game, it costs the user no in-game currency. Sort of a content-bypass here, but a fairly minor one.
The more important pack is the "progression pack" which unlocks Renown Ranks 81-100. Renown Rank is sort of your "pvp level" in WAR, and determines how much PVP power you have and access to PVP gear. Thus, only players with the progression pack can get past level 80, and only they can buy the 80+ PVP gear. This is massively unbalancing, obviously, so anyone who plays WAR seriously will have to get this pack.
That, in itself, is nothing new or unexpected. In any MMO, whenever an expansion is released, it's generally required content. It's hard to imagine anyone playing World of Warcraft without Burning Crusade or WOLK, let alone compete in PVP locked 10 or 20 levels below anyone else. What's interesting is that this pack only ups the Renown Rank and not the actual level, which remains capped at 40. There is no new content: no new areas, no new zones, no new quests; just high rank and gear that you get using already-existing scenarios and battlegrounds.
In effect, you're paying $10 for a level cap increase.
WAR is already somewhat unusual in its paniful hybrid of PvE and PvP content, but I think this sets a curious precedent in online games. Level caps usually came along with content expansions: the whole game would expand outward. Now, this progression pack, shows how you can force your players to poney up a bit more cash for a pure level cap increase and relatively little cost to the developer of the game. Heck, it's not technically unfeasible to release a 20 renown rank cap increase every single month with little thought gone into producing it.
The scariest thing is that this sort of patch-like level cap adjustment is usually something that's done for free. Final Fantasy XI is upping its level cap from 75 to 99 (5 levels at a time) free for all users. They've got plenty of add-on packs to buy, but they're all content, not mere game mechanic unlocking. WAR is the only example I can think of where a subscription-based game forces players to buy an add-on that does nothing but up a level cap.
I'm just glad I got gifted both packs. Now to sort through these 29 mails of vanity pets, mounts, and other sundry tokens. Yay!