I can relate, I bailed on the instructor gig about 15 years ago, and have also taken a renewed interest in the last couple years (with a hankering to head down south again, at some point.)
During my run, I watched the proliferation of things like nitrox, (and tech diving in general), computers, integrated BC's (as well as the shift from calling them BCD's, LOL!).
Also, a few once well known companies have fallen by the wayside (Dacor,etc), while others have appeared or moved up and become more well known (Atomic, Zeagle,etc).
But, I still have kind of an old school view towards dive gear, preferring simple, tried-and-true designs, over the latest/greatest.
I owned wings/backplate BC's back when i was actively cave diving, but i still like (simple,economical) vest-style BC's for regular diving, even though they seem to be dismissed as kiddie toys around here
. They're simple, cheap, and they work, nothing wrong with them at all.
As mentioned above, older regulators can still be quite solid ( and in some ways even better), and I'm still a fan of the older Sherwoods I used to use back in the day, and have snagged several minty-nice ones on ebay in the last couple years, and lots of guys here love the older Scubapros, Aqualungs, etc. A lot of solid old gear still floating around, and fairly cheap.
Lights (and batteries) are one thing that have truly leapt forward. What was once a big, premium, name-brand, state of the art light, is now almost considered junk.The new LED lights, and rechargeable batteries, just blow away the lights from a few years back.
But the dive industry is just like any other: Their marketing and design teams are constantly over-thinking things, coming up with goofier and goofier features, largely designed to separate the uninitiated from their money (fin designs seem to get an inordinate amount of their attention, followed by BC's). I wouldn't get too caught up in what's "new".
Like with any new or resurgent interest, it's always a good idea to first do a lot of reading before taking the plunge, but for the most part, dive gear has long been figured out, and simple, inexpensive, tried-and-true designs generally work just as well as the more expensive newfangled stuff with all the pretty plastic, over-engineering, and marketing hype.