I completely agree with this.
I beg to differ. Yes, long time readers have said they felt it like an insult that a new character gets a solo, but from what I've seen, it's not to complain that Peter Parker or Tony Stark, or Logan, or Steve Rogers doesn't have one. They're more upset that B-characters who have been around for years and years and never had a proper solo book, don't get to have one but new characters do. As an example: the Wasp.
I agree with everything you said, but wanted to comment on the part in bold. Since this is the "unpopular/controversial opinion" thread, here's one.
Fans who say "make new characters" can have another reason for saying this. They say to make new ones because that way, they'll be able to continue reading their favorite character because he or she won't get replaced. It's more "make new, so you won't replace my favorite". The thing is, when your favorite is still being published, you're a lot more likely to pick up new titles also, and as a side effect feel no resentment towards the new character because he or she won't prevent you from reading about your favorite character.