You're right, I started PvP in Season 3. So my experience in 3.x PvP is probably half the time you've experienced it. XD
So most likely there are things I haven't experienced that you have... which in turn makes you miss the old PvP more than I do.
As such, from my experience and perspective (from Season 3 onward), I miss chat... and I also miss the depth that 3.x had (which you can get pretty creative with, especially with bursts) versus 4.x's simplified system. The only thing from 3.x that I don't miss was stun-to-BTE... except when I used MCH. LOL
Other than that, I do enjoy current 4.x (not Season 7), although I feel that the devs should return more depth, chat (w/ the option to mute), and Sprint as a standard ability instead of relegating it to being an additional. That's where I miss 3.x... at least from what I know. haha
EDIT: Actually, I started late in Season 2. lol O.o