Oh sure, there have been very good Hobgoblins - but their characters (you know the people behind the masks) have been nothing special - just a bunch of thugs and petty bank robbers.
The best villains make it personal - Harry as the Hobgoblin would a) make it personal and b) stop the movies from being repetitive.
The comics could get away with using loads of Green Goblins - because there literally tons of enemies between Normans goblin episode, and Harrys Goblin episode. In the movies, there would be, like, 2 enemies in between Harry and Normans goblin - it would seem too close together.
Kraven is just a hunter, he doesn't make it personal either.
Nobody cares about enemies that are just "strong", and the emotion is never there. This is why Carnage, in my opinion, is completely boring, as a character.
Give me Lizard, Venom and The Goblin anytime, they make every battle personal. Doctor Octopus and Curt Conners were very influential in Peters life, and Venom and Gobby know more about Spiderman than anybody. They raise the stakes, make the odds that extra bit more forboding.
The likes of Carnage may risk Spidermans life, but in the end he's just a wild one dimensional lunatic - with no connection to Spiderman. I used to love Carnage when I was younger - but as I grew older I understood that Venom and the Goblin, and The Lizard (his whole deal of Spiderman having to hold back on him all the time as to not kill him) are the best kinds of villain, by a long shot.