It's lousy for bidders, but so long as even ONE bidder is keen on a particular name and has deep pockets, it's great for Pool.
I guess it could also lead to "surgical strike over-bidding" tactics by the big players. For example, if they (privately) would be willing to pay up to $20,000 for a particular name but think that other parties would be wary of the sealed bid process and start low, they might bid $10,000 sealed in the hope that the other bidders will be so terrified by the gap between their sealed top bid and the $10k one that they simply shrug their shoulders and give up in the belief they have no chance. Yes, the $10k bidder ended up paying $10k for the domain, but that was half their max and effectively stopped their competition gradually warming up to that particular name and bidding it all the way to $20k or beyond.
An example:-
goodgenericword.com
Big Player
#1 figures other bidders will start cautiously, and puts in $10k sealed bid.
Big Player
#1 guessed right, as second highest bid (Big Player
#2) was $2.5k.
Domain goes to phase 2, but Big Player
#2 doesn't bother to bid as they think "if Big Player
#1 started at $10k they must want the name SO bad it won't be worth it - I'll save my funds for a different name"
Big Player
#1 gets the name at $10k.