This is definitely to avoid the wire act.
But also, books have wanted to go all internet for a while, but have needed an excuse to annoy some customers.
It is expensive to man phones.
High bets were initially taken over the phone because software sucked (Remember betting after the game was over and such...)
Now that software is excellent and can automove lines, a lot of books have been looking for an excuse to go all web without pissing people off. The DOJ has given them this excuse.
(This is like the .net - keeps you out of trouble for a little while, but really meaningless if you've been taking phone bets for 10 years.)
I assume the raised the online limits?
-Sean