Both formats have luck and skill involved, why argue? I like limited better because of the mystery, anticipation, and surprise. Its also nice to see people play different cards and not know their entire deck +/- 8 cards after their first drop.

Because it's fun?

Couldn't say. I used to play four different CCGs where I ranked in the world top 10 and had complete (or near-complete) sets, and I still preferred sealed deck each of them. Of course, half the reason for that was I didn't like having to search through all my cards every time it came time to build a new deck :-)

One thing I did like about sealed is it filters out the people who have one really strong deck that they've been playing forever and refuse to play anything else; after a while it gets pretty boring playing against them. Me, I like using a different deck every tournament.