I honestly doubt the actual ttk has changed much.(note that I haven't looked up data on this so really I'm just going by opinion/speculation/guessing).
The real difference is the lack/restriction of ohk capabilities and more reliance on your primary which naturally takes more hits to kill. D1 had long ttk if you weren't using shotties, snipers, and the weapons that made whatever meta it was.
In short if you wasn't using specials and the top 5 (probably could be stretched to top 10) regular weapons in the game for primaries the ttk wasn't really an issue.
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In the beta you actually have time to engage and disengage, the fact that there's no more Ohk weapons makes it have a slower TTK, that part feels good, don't get me wrong, I loved the days of the sniper and rushing titan w/shotgun and shoulder charge but to me it always felt like something that you had to do to stay ahead, in D2 there's fun in the gunfights, whether you lose it or win it.