Well, if you're asking about why people buy books then you're really on to a different question.
Like I said earlier in this thread, there was a trend for a while for Marvel to move new characters into the established books, and shift the classic characters out to launch new titles. Undoubtedly that was to get existing readers to keep reading the old book with the new characters, and let them launch new books with characters that people already wanted to read about.
Launching Miles as Ultimate Spider-Man got him more readers than he would have got as Termite-Man, I'm sure. So marketing is a part of it. But if the characters are much more important than the codenames and costumes, it presumably doesn't make any difference to you that Marvel are using an existing name for the character partly as a sales tactic, does it? If the story is the same either way.