DDO went down a very strange design path in this respect. In most role playing games, characters possess a very limited number of cures and 'breakout' skills, typically on long timers. A player must use them very wisely in more difficult battles or risk serious consequences.
DDO challenges players with all the usual suspects--holds, paralysis, slows, damage over time effects, and so forth--but then offers easy access to cures and prevention items for practically everything. As a result, players can laugh off special attacks that would force critical decisions in other games.
This easy access to cures and prevention items severely limits the ways developers can challenge player characters so they pretty obviously created a bunch of house rules to liven things up. Players then complain about the house rules. The developers respond with better cures and prevention items, realize they constrain challenge options, and along come a new batch of house rules. Round and round we go, arriving at the very convoluted system in place today.
The developers could make all cures and prevention items work 'properly' but that would result in a very bland and uninteresting game. Yanking easy access to cures and prevention items would trigger a gigagigantic player uproar. Therefore, I strongly anticipate house rules will remain in place.
