Returning Player (Sorry)
HoT will give you access to the elite specs will give you better options to be more competitive. That isn’t to say you can’t be competitive without them, but it will make it harder.
If you mainly play PvP, you’re mostly going to miss out on the new elite-specializations. They where pretty powerful when HOT came out, and I’d say they’re still a bit too strong compared to the core builds, but not insurmountably so. I think you’ll also miss out on some runes/sigils/stat combos, but not entirely certain.
For WvW it’s a bit of the same, but getting the “best” stats and runes/sigils etc can get pretty darn expensive. Thankfully they added a way to unlock the Elite-Specializations in WvW (the yellow currency thing that I still can’t remember the name of…).
But some classes is pretty dominated by their elite-specializations, DareDevil for example more or less replace core thieves. While other classes such as Guardian can do very well without the Dragonhunter, and the main zerg build is still core guard. The main roaming build is DH though.
TLDR: You can manage without, you’ll get some advantages with, but for the most part not super big. For WvW you might have to grind PVE for weeks to get some of the best gear stuff.
“Understanding is a three edged sword: your side, their side, and the truth.”
“The objective is to win. The goal is to have fun.”