I think this might be a real issue for "caster" classes. Like smugglers, BH etc. But I'm also thinking that it could be that in WoW we had a lot of addons. There is the specific addon that do the account for latency so that you could chain and combo abilities better. I can't remember the addom. Spellcaster maybe or if it was like Castbar?
It could very well be those kinds of addons that has made WoW feel so much better in these aspects?
I played a warlock in WoW as my main for a few years, and were in a couple of highend raids in vanilla and TBC, never did PvP much, and I kind of notice what it is that the OP talks about. And I fell it is most noticeable in the Warzones.
So maybe, if an addon, like the ones who exist for WoW, comes to SWTOR, this might not be an issue anymore?