I'd agree with this as well.
I loved playing Brood War casually, and perhaps because of the less rigid matchmaking I was always able to find opponents where I was able to use a sort of personal strategy that had a decent chance of winning.
With Starcraft 2 though, especially now that the player base is older and more practiced, every match feels like a struggle to optimize every single second's worth of action.
I played again a few months ago, and even in Silver League I was encountering the same decently executed builds over and over again which basically necessitate a certain specific counter.
And even though I was better than those players, one inevitably moves up the internal rankings (whether the actual ladder or just unranked) and before long is facing opponents where you absolutely must play incredibly well or you simply have no chance of winning. A single slip up at the 32 minute mark and you lose 100 supply in the span of about 5 seconds and it was all for naught. Perhaps even more frustratingly though is the number of highly optimized builds that seek to kill you as fast as possible. When the build is literally being executed with second to second timing, there's not much room to be creative on the fly.
Basically, it felt like I would need to spend hours of a day several times a week basically studying and practicing the game just to be able to have a chance at winning 50% of the games.
That's... just not something I have time for or interest in anymore, I guess.
I'm pressed for time, but additionally...
The art style still doesn't sit as well with me as Brood War's. It feels less "gritty war" and more like "toys come to life to fight in space".
I personally find the campaign story to be cringeworthy, though the actual mission gameplay is generally okay to excellent.
Certain elements of the actual way the game controls don't sit right with me. Stuff flows almost "too well", and it feels almost too easy to just have a massive clump of marines and medivacs that (at low levels anyways) is surprisingly difficult to deal with just due the sheer DPS potential. Stuff like that.