Heck, I have a new ('21 RT) one and it's been the easiest bike to work on than pretty much any other bike I've had (Wings, Super Tenere, Tracer 900, VStrom 650, ST1300s).
Valve checks are simple... I did buy tools from a guy that fabricates the ones you need but they were a fraction of the cost compared to what you'd have to buy from BMW and he has videos on the process. The OBDII connector gives you all the info you need to reset the maint interval or check codes and it will even pulse the brakes after a fluid change to help get all the air out (haven't tried that yet). I connect to it with a BT OBDII and a motoscan app on my phone or tablet. Yeah, it has tons of tech but it all works and works well.
I held off getting the RT because of all the things you hear about BMW bikes like final drive issues, electrical issues, etc... however, EVERY bike has issues, there's not a single one out there that doesn't have an issue, weak spot, design flaw or something that may drive the owner crazy... lol 'er'
This is my first BMW and I usually get bored or start looking for a replacement for the current bike 2-3 years into ownership for some reason, too heavy, too light, short range tank, bad ergonomics, wind management... etc... This bike has been the best so far and I'll think about maybe getting a 2nd lighter bike for short local rides but then I get on the RT and it's just perfect.. 100 miles or 1100 miles it just works and all the tech works well too. I say that with the exception of BMW's Connected App which is hideous so I don't really use it, the Zumo XT is good enough. They should have allowed mirroring for Android Auto and Car Play, that would have made more sense - kudos to Honda for doing that on the Wing.
Anyway, this has nothing to do with older BMWs ... more about BMW in general.
But, if I was looking for an older cheap and good bike.. The VFR 750/800 would be what I'd look for...