My "problem" with parrying as being an expected tactic to balance attacks out is that it only works for melee combat, where you get to apply skill-to-skill (plus some bonuses like shields and whatnot).
When you start hitting ranged weapons and modest to high level (or power level), the paradigm collapses. Our primary RM/SM party rapidly scaled out to the point that cover bonuses just didn't cut it (especially with the high-end AE weapons in use) especially since you got more attack rolls per round. So I started letting people use AD apply to ranged attacks. And then of course shields, and it ended up in an ever-increasing mess of rocket tag, as whatever you do, or cut out, it ends up nasty (especially since in SM2 you only got half your parry bonus to DB when ranged parrying and I'm not even sure you were allowed to do that in SMP...) And, of course, if you have a party with an average superhuman speed, you always want to get hat first strike in anyway...
My current rules say you benefit from ranged parry (which no-one ever does, except for the Jedi), and any two of AD, cover or shield (i.e. force screen, not scutum!) I'm not sure there is a good solution, unfortunately.
(And I've given up pretty much anything other than throwing chaff encounters at the PCs, since no boss monster has ever managed to get anywhere without being open-ended fluke-critted to death in short order, even when I stacked insanely in their favour...!)