To use a 2002 as a DD, I should think you'd want to have at least basic mechanical skills, some basic tools, and the ability to trouble-shoot and fix anything that crops up as soon as it crops up - or at least take it to a specialist and have it fixed. I mean, these things are up to 45 years old and they will have issues from time to time. Parts availability is something to look into. Through vendors like Pelican Parts, you can get anything you need for an old Porsche, for instance, but that does not exactly appear to be the case for old Bimmers. Pelican, which has outstanding service, does have a few things for these cars, but their list doesn't seem to be nearly as extensive as their Porsche parts lists. Perhaps there are other vendors who do have extensive parts supplies?
Keep in mind also, as others have mentioned, that you will not have air conditioning, or at least will not have a system that works satisfactorily.
This is important - keep in mind that the safety stuff we take for granted in modern cars - air bags, door protection, crumple zones and all the rest - is totally absent in any car of this vintage. And they do not have the brake pad sensors that tell you when the pads are worn out. Ask me how I know - yes, I was young at the time and even dumber than I am now....
All that said, these are solid, reliable little cars that are quite easy to work on, fun to look at and even more fun to drive. You just have to have, or develop, some mechanical sympathy. My next old crock - I'm currently on hiatus from old cars - will be another one of these.