One aspect I haven't seen mentioned here is archives and clone kits. I would say ~95% of Estes OOP kits have been completely and professionally archived on JimZ Spacemodeling website. The Centuri kit collection is a little less complete, but most of the popular/familiar kits have all the info needed to build. Instructions, fin templates, parts list, decal scans, it's there for any rocket you'd wish to make. My favorite is looking through the old Estes Designer of the Month rocket plans, I love seeing the creative things people were coming up with in the 70's and replicating them myself. Ninfinger also has most of the old catalogs archived as well on his website, for Centuri, Estes, and other smaller companies. If you ever feel nostalgic and want the feeling of leafing through a vintage catalog, print it off and reminisce
Fast forward a bit, and you had companies like Sunward Aerospace designing flying pyramids, flying Umbrellas, and fighter plane styled rockets in the mid 2000's. A lot of other smaller companies came and went like Edmounds Aerospace, with most of their plans being archived on JimZ website. Also during this time were independent designers popping up on the rocketry forum, utilizing programs like OpenRocket for new exotic designs. Shrox was REALLY pushing the boundaries on what a rocket is... his builds included ping pong balls, CDs, asymmetry, disjointed body tubes, anything you can think of. I feel like this has carried on into guys like Neil W; I look at his designs and just drool sometimes!
Finally we are in the current day, where all of this info is readily available, parts aren't too hard to get, and the possibilities seem endless from my perspective. While the past may have been simpler (look through the Estes catalog for a cool rocket, buy said rocket), I'm not sure if that's exactly better. I think there has been a lot of development in the field of model rocketry, and we are at a point where there aren't many limitations. Anything from the past can be brought back (except for some niche things like B14-0 motors), and new things are created and shared everyday. That's just my 2 cents as a guy born after the 90's.