> most useful thing ever ... seed life on another planet

I don't intend to change your mind on this point, but I'll just say I disagree (:

Why not pave over national parks and build more cities? Seems "useful"...

This is very much a "Red Mars / Green Mars" sort of debate (see the books by Kim Stanley Robinson; not that I'm a huge fan, but it's very topical).

You'll always have some people who want to forcibly mold the world/universe into something else, and some people who want to preserve what's there, and a whole spectrum in between.

If nothing else, once you do contaminate/bless Mars with life, there is no going back. So, it seems reasonable to take advantage of the unique opportunity to study it before crossing that line.

Just my 2¢