I think part of the love comes from the fact that the older markers seem to be a lot higher quality than most of the new stuff. ie an old brass sheridan is built to last and for the price is a better marker than most $100 markers out there. A factory PGP might not be feasible with todays paint but throw in wedgits from palmers an RVA and a valve tune and you've got yourself a competitive marker for very little money. Not to mention playing with older markers is just plain fun. I find the newer markers also encourage relying on firepower and modes rather than skill to play the game and I'm sorry but putting a high firepower marker in the hands of basically a child is a recipe for douchebaggery central. If I had my way and thankfully I will with my own son kids would start off with stock class pumps in the woods. Learn about conserving paint and air and rely on skills and stealth and brains to win. After they have mastered that I'd move them up to OC pump where you can lay paint if needed to get out of a jam but still emphasize skill and then lastly after that finally let them play semi and I've found that introducing kids that way (and i have introduced a few using this method) makes for kids that are amazing at the game with great skills but amazing trigger control and also a great attitude.
a bit off topic but I think you can see that old school markers have a great place in the game even the modern game and I hope they stay around for years to come