I can certainly understand your position that Ma.tt doesn't have mostly content relevant to WordPress news these days, and wanting it to be removed from Planet WordPress. However, the argument could be made that, unlike many other highly used utilities, WordPress has a creator who is close, reachable, and more personable. Anyone who uses WordPress is immediately exposed to its creator's personal life, something which is rare in far-reaching companies.
Aside from that, it's his software, why wouldn't he want to use it as free advertisement for his blog? NextGEN Gallery's main page has the feed for Alex Rabe's personal blog as well. Of course, you can always easily change the feed shown in the Dashboard.

Michael Torbert’s last blog post..You know you’re a WordPress addict if…