I personally agree with you. Timegates allow players to take their time on content instead of simply trying to rush through it in order to get to the rewards ASAP. This is important in an MMO where the game is about immersion, about exploring, reading quest text etc.
To me one of the most obvious missing timegates in recent times has been Pathfinder part II. Pathfinder part I was a completely unstressful achievement to get. We literally had a year to get it done, and most people got it within a few months anyway. Then they finally introduce flying with a straight up requirement of doing a rep grind in Nazjatar and Mechagon in order to unlock flying everywhere. So instead of players taking their time to savour the content, it was all about rushing it, grinding, playing it to death for an insane 2 weeks - by which time most people hated it.
It would have been far more sensible to release a short 10-15 minute questline to enable flying in Kul Tiras and Zandalar for those with Pathfinder Part I and put a 4-6 week timegate on flying in Nazjatar/Mechagon (or else remove the grind requirement altogether). That way people could have taken their time in the zones and do them at a pace determined by what is most enjoyable rather than what will get them to flying the fastest.
Obviously timegating for the sake of getting people to stay subbed longer isn't good either, but in all honesty, I don't see that much in WoW, and IMO most of the complaints about artificial timegating just to get more subs are reliant on conspiracy theory type reasoning. Granted, I am not the kind of player who likes gorging on content so that I can be done and then unsubscribe. I find that WoW has so much to do in it that when I am done with the timegated stuff, there is always more than enough other stuff to get to.