Although not really unexpected, I still have...mixed feelings for this matter. As it seems we're talking PvP here...
On the positive side: first and foremost, PvP mechanics will surely shift, as removal of ITD means no more OHKOs or unescapable combos that result in the same, really. (Take Vanq/Sorc, for example.) This is obviously good and will finally make PvP combat, whether 1v1 or mass, more interesting, long-lasting and...tactical, if you like. This is a significant improvement.
Second, this will give a reason to build Defense (not just stack Damage Abs.), allowing more gear flexibility (= good); far as I've seen, it's largely ignored right now. (pun intended)
(PvE-wise, reduced burst damage will prolong pack/boss fights as well, raising their difficulty.)
On the negative side: foremost, it immediately comes to mind that you are going to revamp Vanquisher [and, possibly, Windwalker] class should you remove ITD - those classes heavily rely on it. (Not because they can't fight w/o them, just because ITD was the core of their mechanics.) I, for one, don't really see any substitutes for this mechanic except probably something involving Crit...but I guess it's no longer my concern.
Second, speaking of Crit: as with ITD removed, it will be the only thing multiplying attack damage, it must as well be entirely rebalanced to provide effective counters (Protection) for it, as it is at the moment heavily underestimated (and rightfully so, as usually a person's Crit chance exceeds the likely target's Protection too far to somehow counter it).
Third, as many have mentioned before me, it will be substantially harder to kill tanks and/or healers. I know they indeed shouldn't be killed in 5-7 hits, but with the durability they currently have they will just wear the target down (1v1) or request focus fire on it (mass); they shouldn't be nigh-invincible, either. While there are specific classes that counter them (say, Crusader, whose bleed damage cuts through Templars' shields, Champions' reflects and Priests'/Prophets' heals.), there should be at least some general mechanic through which other classes can damage them. ITD executed precisely that function.
[to avoid tanks/healers raging on me: I did not say "mechanic to allow other classes to easily kill them", I implied "something that counters high defenses and/or healing" - this isn't the same thing. Remember, everything has a counter.]
Overall, my stance is neutral, leaning more toward keeping ITD.
I personally think it's better to invest your time and effort to try to fix the bugs with it, rather than just removing it altogether (if it's actually possible to fix them, that is.). It's too great/versatile a mechanic to just drop it.
My 42 cents.