re: .30-30 Winchester. Why so unpopular now?

I dont think the problem lies with the cartridge so much as the lever gun being seen as an inferior or antiquated firearm. I think the same goes for revolvers vs automatics. Like anything else it's always what's new an en vogue. Right now that's high tech looking semi autos and bolt action sporting gun/cartridge combos built well beyond the abilities or needs of the average shooter/hunter.