I feel that sentiment. It's not that I mind people doing new apps in already crowded market segments - it's that messaging apps, like social networking sites, work on network effect. I don't want a new messaging app for the same reason I don't want a new Facebook - the existing one is awesome enough, new ones don't offer anything interesting, and I definitely don't feel like rebuilding my contact lists every other year.

In this way, a new app is a danger not only to the maker of an old app, it's a danger to the client as well.