This isn't City Of Heroes
City of Heroes wasn't even immune to the vast overvaluing of specific set ups; the removal of nominal roles simply made it so that support classes were *vastly* more valuable than otherwise specialized roles. The large scale imbalance in the design forced the developers to largely abandon the "anything goes" balance used early on and instead focus on hyperspecialized mechanics that required specific loadouts for anything that wasn't supposed to simply be able to be roflstomped by a full group of support characters.
The problem with generalizing roles to the extent that you're suggesting (giving everyone the same damage/survivability with little variation except for 1-2 abilities or secondary effects active only as specific times) doesn't really encourage teamwork. Teamwork is accomplished through specialization. Generalization simply ends up having everyone essentially play "solo" together. Attempting to force players to play operate tactically (moreso than they already do by assigning CC targets, adapting to specific mechanics, etc.) by reducing their ability to specialize would actually operate contrary to your intent.
This doesn't mean that I think that some degree of generalization wouldn't be untoward, though I honestly think that tanks and DPS are in reasonably good straights already: tanks and DPS both represent excellent ratios of damage and survivability and accomplish their goals explicitly by beat on targets. Healers really just stare at red bars all day (which gets really old really fast). I would *love* to see healers encouraged to use attacks as part of their maintenance healing rotation. Imagine if Commandos healed their Trauma Probe target (without consuming the stacks) whenever they dealt damage with Hammer Shot (small enough that they would still need to throw out actual heals except in the most overgeared situations), and Sages bounced a small amount of AoE healing to allies near targets they hit with Disturbance (which would be made free with the same talent that causes the healing to occur). Presumably something else could be contrived for Scoundrels, but I couldn't think of anything.