You know, I used to have the exact same opinion as you, until I actually tried one. Five minutes into the first ride I knew I was full of it, that my opinions about snowbikes were not based on fact, but rather the fear that I had spent money in the wrong direction.
YUP.
I'll admit the few I had seen before a month or so ago I thought were a bad joke. They were guys trying to ride them like sleds... and doing it poorly.
About 20 min into riding one myself, I did my 2nd climb, wasn't going to make it, and turned... yeah, right about then my ideas of bikes when POOF. HOLY CRAPBALLS BATMAN... these things can't climb in pow worth a crap... yet they can go up pretty much anything... how can both of those statements be true??