Currently(or soon to be) Reading: Alan Scott: Green Lantern, Batman/Superman: World's Finest, Fire & Ice: Welcome to Smallville, Green Arrow, Green Lantern, Jay Garrick: The Flash, Justice Society of America, Power Girl, Superman, Shazam, Titans, Wesley Dodds: Sandman, Wonder Woman, & World's Finest: Teen Titans.
Indeed, they were more successful, back then...
But the world has changed. Every year editorial demands a new 'Crisis on Infinite Earth's' level end-of-everything 'event', and the villains of those events need to be multiverse-destroyer level threats, because the bar has been set so ludicrously high. They rode the tiger and are afraid to dismount.
I think god-like villains and the 'ZOMG NOTHINGS GOING TO BE THE SAME AFTER THIS!!!" events they bring with them are so boring.
Reading List (Super behind but reading them nonetheless):
DC: Currently figuring that out
Marvel: Read above
Image: Killadelphia, Nightmare Blog
Other: The Antagonist, Something is Killing the Children, Avatar: TLAB
Manga: My Hero Academia, MHA: Vigilanties, Soul Eater: the Perfect Edition, Berserk, Hunter X Hunter, Witch Hat Atelier, Kaiju No. 8
Look at the first three Die Hard movies. Each succeeding sequel, the scale of the villains' plans increased, and yet at the end of the day, two of the three viilains' plans were about stealing money and getting rich, while the middle one was basically a "Screw you, world, for changing politically" bit of protest (and also murder, mass murder, and terrorism). You telling me today's writers can't make a compelling story about villains motivated by greed or reactionary politics anymore?