As far as number of characters are concerned, in the context of an RPG, I would prefer a smaller number of characters with more time spent towards developing said characters. Rather than a myriad of potential companions/cohorts with not much in the way of "personality." What I suspect - I haven't read DA's forums really, or much in the way of dev interviews - is that Bioware has heavily invested their various NPCs that can recruited into the core plot. Subsequently, I suspect that their choice to discard a more permanent style of death is two-fold: one, to appeal to a greater demographic of gamers (i.e., those gamers that find "death" to be a trivial and pointless inconvenience - decline amirite?), and so that whatever facets of plot and the writing involved around those companions/NPCs won't be missed by potential players.
One aspect of death in any game is a question of character resources. In a game like Fallout, for instance, reviving a character wasn't even a concept. Death was death - the end. In BG, reviving a character, given the limited resources of the character, was expensive, difficult and likely time-consuming. Barring a simple reload, that often laborious process was actually, I found anyway, quite enjoyable. In BG2, however, death was a minor inconvenience. That rod of resurrection, of which I believe there were multiples of throughout SOA and TOB, made death no more than a two-click inconvenience.
I whole-heartedly agree that if death is to make any sort of impact in a game, it has to be more than simply a question of how readily a player can rectify it, or how costly it is. It has to has some effect "in game," rather than just inconvenience the player. Furthermore, I'm of the opinion that this new system of "get up after the fight" just isn't a well developed solution.