I think you underestimate the amount of time, effort, and skill that goes into making new content and systems. Even back on live content updates were few and far between, and Cryptic/Paragon had a staff of full-time workers. Not to mention the fragility of the code base and how trying to add a new system could very well break other things in unexpected ways. And while the idea of a Nemesis system was pretty cool, the CO implementation was kinda meh. A lot of potential that was never reached. There are some good things in CO, IMO it's an enjoyable game to play casually as there's some nice content and mechanics there (along with some really nice costume pieces and character builds you simply can't do here), but CoH is overall a far better game.
I think we would all love to see massive updates, but honestly I'm just thankful to be able to play again and am grateful for all the hard work the HC team does to give us new stuff and QoL additions whenever and wherever possible.