You're massively confused. The writing is not any better or worse. Some comics were well written, some weren't. The only difference is they are spreading themselves a little too thin currently.
They were literally just throwing shit at the wall to see what sticks. Or they were just trying to capitalize on what they thought was cool then. Blacksploitation and Martial Arts flicks are "big" well we gotta capitalize on it!
Do you honestly believe when they created Wolverine they knew they were sitting on a gold mine? No, he was just a throwaway character in a Hulk comic with a crap yellow(!) costume and a goofy animal name.
I sometimes wonder how Len Wein managed to stumble upon creating the New X-men (OG SJW TEAM) because his work before or since doesn't really indicate it.
Good writing is important but let's not forget that writing is often in the service of doing something that's usually very derivative. Still you can take a character with a derivative name (Ms Marvel) and turn her into a well realized character.