I think the main reason why a lot of wrestlers wear short tights is because (no homo) they are in great shape and want to show off more of their muscles than in the past. You don't have that many Earthquakes or Typhoons running around in the WWE.
As far as rip offs, I don't see Jack Swagger as rip off of Angle because of the singlet, he is more of an Angle rip off doing the Ankle Lock just Angle ripped off Shamrock with that. If a guy wears pants to the ring, I don't think Hardy as the Hardy boys always looked like Backyard wrestlers anyway.
It's the wrestlers choice what to wear, some good, some bad. I would love to see John wrestle in more traditional attire and I think it could fit his gimmick.
As for trying something new not getting over, thats dumb, as that is what usually gets guys over. Look what Jericho, Orton, Miz, Cena and Punk did. All of them tried something different to get over. Sure you can find a wrestler from the past to compare to, but they all made it their own without being a rip off. Plus in wrestling, ripping off a guy is great as it should how great the gimmick was and still can be.