'There was a time.....' when Marvel had about 12 Big Gun Villains like those named above as well as the Mandarin, the Grand Master, Annihilus, Magneto, Ultron, Immortus, the Leader, Dormammu, the Collector, Kang, Attuma (and that's pushing it on this list), and a few others...
....and then an additional HUGE cast (like, over a thousand) of viable, deadly, and dangerous 'lesser' villains who were taken with Utter Seriousness by the writers, and these included Electro, Mr. Fear, the Cobra, the Sandman, the Grim Reaper, Kraven the Hunter, the Living Laser, Mesmero, the Jester, the Petrified Man, Llyra, Mastermind, the Purple Man, Doctor Octopus, the original Zodiac and Scorpio, Titania, Dr. Dorcas, Mr. Hyde, the Vamp/Anima, Spymaster, Mysterio, Firebrand, the Wingless Wizard, Medusa, the Savage Land Mutates, Madame Masque, the Man-Bull, the Flying Dutchman, Sunfire, the Scorpion, Blaastar, the Viper, the Eel, Commander Kraken, Moonstone, the Owl, Diablo, the Basilisk, the Grey Gargoyle, Tiger Shark, the Melter, Klaw, the Enchantress, and all the rest.
I can only assume you missed this decades-long period when most of Marvel's villains were less-than-first-tier in terms of power and world dominance. They were essentially characters out of Romance, and would never be portrayed as walking about in their bathrobes, farting, belching, and frying eggs. They were mysterious, calculating, powerful, unknowable even. They weren't objects of 'fun.'
Today, we live in a very unimaginative, flat, prosiac (at Best) age, when it's popular to shit on and tear down all things Better than what the current generation can and has been able to drum up. Almost everything is irony, sarcasm, and attempts at droll 'wit' and 'humor,' like what we see in Bendis' New Avengers. Spider Man's going to poop his drawers! Well, my. Cover your eyes and pull your daughters indoors fast.
Aunt May I can see in a bathrobe, or Mary Jane, or Peter, Scott, Jan, or Bruce in the morning, but No, it's pretty pathetic (and not in the manner intended) to have the Man-Ape walking around in a bathrobe OVER HIS COSTUME. That's just making a mockery of him--clearly. It's saying, 'This guy is a pathetic idiot, under no circumstances to be taken seriously.'
Consequently, where is the drama in the story? We already know the GR and the Man-Pae are idiots, we've practically been told so outright.
And if you're going to give me the argument that the villains listed above and their peers were always losers, well, No, that was not the case; and excellent writers took even these lesser (that's 'lesser in the GRAND scheme of things') villains like Sabertooth, the Green Goblin (who was, at one time, simply one of SM's enemies among many), Mastermind, and Kraven the Hunter and brought them right to the fore of some very powerful and influential stories. Look what happened to Jean and the X-Men as the result of the 'pathetic Mastermind.'
Which is to say that the potential of any given character is in the creator's eye, and not in the character's boilerplate.