I can see how having 300 people right on top of each other might be a problem... but try to appreciate what it is like for the off-peakers...
Chasing flashes dar bar hoping to find a fight, only to find a single low con.
Finally finding what looks like a fight, taking off and getting there only to find it fizzling out or gone completely by the time you get there...
One of the reasons I quit AH was that, given my schedule and responsibilities at the time, when I had the chance to log on for an hour and have quick go I'd spend the entire time looking for fights.
It may just be unfortunate for me that my regular playing time coincides with the absolute worst time of day to play AH.... but that off peak arena really helps people like me get a fight.
Forcing all 150 people into one arena is the only way to handle total player numbers less than 200.
Long live the off peak arena!