Well, if you have trouble beating an enrage timer, more often than not your group is not geared enough.. regardless of how "veteran" and "awesome" you are as MMO players.
That being said, yes some of the HM bosses are overtuned, but if you guys rolled it your first or second time in you would most likely be here complaining that it is too easy and you have nothing to do.
Our guild is a group of very experienced MMO players and we have found that as far as enrage timers: DPS scales remarkably well with gear in this game, and when we have had trouble with an enrage timer, just a couple days later we have blown it apart with a few gear upgrades.
All in all, I will just default to: If it was easier you'd complain. It's too hard so you complain. I'm sorry that there isn't a good middle ground for you. (Not being facetious either)
Not true. Our group is perfectly capable of killing the mob - it is down to 5 percent health, nobody is dying and everything is stable.
Suddenly some arbitrary 'timer' kicks in and decides that even though we have no issues with the mob we didn't kill him in 5 minutes so we suck. That is a stupid, arbitrary and ultimately worthless distinction that does nothing to enhance the game.