Grandfathering in is a common thing. The one consistency with fan expectations is the dramatic inconsistency and rose colored glasses around continuity.And once again I'll note that it's a weird double standard that most fans have no problem discounting Data saying in "Encounter at Farpoint" that he graduated in '78 but him saying that Admiral McCoy is 137 years old in the exact same episode is somehow sacrosanct. Either keep both numbers or throw them both out.
This is my experience as well. Trek is change. It won't be any different because TV shows change a lot as development goes on, much less multiple series across the decades.Some fans may indeed expect, say, that the Klingons always look like they did in in Berman era, whereas some of us, who grew up watching TOS-era Klingons, long ago got used to the idea that there's no such thing as a "real" Klingon, that the makeups and costumes are going to get refreshed every generation or so -- and that's just the way it works.
Hell, my favorite show of all time is MASH and it gets character details wrong. It's funny to me to watch Season 1 all the way to 11 and see how Hawkeye's backstory changes. Is that show somehow lesser for it?