Running servers is an expesive buisness
Some games also have GMs involved in events and the likes - they need to be payed. Customer support needs to be payed and so on.
But the money also goes to the development of patches with alterations, additions etc, and continuesly attempting to balance the gameplay (although some "patches" are so large they are a new expansions
)
And balancing of gameplay is something that is not as commen in most other genres
One recently released patch for DAoC gave players and guilds the options to own houses. Not something I were interested in - but many others were. Other patches (to come) will re-construct the Realm vs. Realm combat for the game - meaning an overhaul to all areas and other related facts. Abilities are added (or removed/altered if found overpowering etc).
Games migth not change framework per se, but there is a lot of alteration going on still.
As for loss when you die, EVE-Online has some heavy penalties in regards of death combined with an almost full PvP setting. Some skills will take a very long time to train in that game, and dying can make you loose skills. But no MMOG. can survive with a to harsh PvP setting - for instance with permadeath. Much in thoese games take a long time to acomblish and having it all taken away, for instance due to lag-deaths - is harsh.
But MMOGs are not for everyone - but the expense of paying around $10 per month is not staggering, when you look at the amount of play time you can get from the games, compared to many other games play time wich seems to be decreasing for "single player" games.