It only requires that many consoles if you want to play all of the games in a round at once. If you had [# of players]/4 consoles and played each round as two "waves" I think it would still go pretty smoothly. However, it's still a lot of setups for a decent sized tournament.
Play more games. 25% of the people aren't out of the tournament after two matches like double-elimination.
Seeding is less important. Things somewhat sort themselves out as the tournament progresses and you play people with the same record. More games also give a better basis for establishing future seeding.
More hardware required.
May take longer to run.
Someone always gets screwed on tie-breaks.
I'd like to see it tried out, especially if someone's running an on-line tournament where the hardware isn't a limitation. There's a lot of mental inertia to overcome doing something other than double-elimination though.