+5 resist all

This is getting to be a pet peeve. A game will have several different kinds of damage but inevitably players will be given abilities and armour which defends against all equally. It's sloppy design. Defending against a particular damage source is meant to reward player foresight and planning. Restricting all the damage sources after a game's launch is an obvious effect of catering to the simple-minded.
What's truly annoying is that most of these games really do start out with simply too many types of damage. There is some merit to the later restrictions. World of Warcraft had i believe five magic types plus physical damage, plus poisons and curses and i forget what else. With so many damage sources, of course they will be trivialized and the "+resist all" gear will be the most valuable. It is irrational to expect players to predict each others' preferences when there is that much freedom of choice.
The magic number seems to be around three to at most five types of damage. EVE's four-corner system provided a very nice mix of variety and predictability. Knowing your enemy's ship preference also gave some hints as to weapon preference, enough to reward focusing on a couple of resistances out of the four but not completely remove the element of surprise.
For non-MMO multiplayer games, even two separate damage types tends to be enough, as players have less time during a single match to predict each other and respond to shifts in tactics.

The same principle applies to any area of a game where the player must make predictions of his enemy. Take crowd control for instance. Three or four types of crowd control should suffice, each with its own specific counter and no 'protection from all' defenses. This would cover, say, stuns, roots, silence and disarming.
The same applies to specific classes of effects players can use. Poisons, curses, bleeding, etc. all sound nice but they end up as largely redundant in terms of the player response. It takes too many combat actions to deal with specific effects so it's more efficient to simply heal through everything. It would be better to associate these effects with specific damage types. Curses, for instance, would be the only effect associated with 'dark' or' shadow' damage so that they can be dealt with either through resistances or a 'remove curse' ability. Bleeding might work best as regular physical damage and be automatically removed by a healing potion.

Complexity is always preferable, but it is self-defeating when the many options blend into one pattern. The reward for being able to predict or respond to one particular damage type has to outweigh the bullheaded approach of tanking and healing.