Each card from Alpha or Beta is worth some money, especially those that are powerful in-game or that have special nostalgic value, like fan-favorites Serra Angel and Shivan Dragon
The choice is still there, however, to see three cards deeper into your deck and add any powerful card you just so happen to mill from it
I do quite like it, but I definitely agree that I think he's going to require a good bit of draw/hand manipulation to make sure you can actually curve out with him properly and not have a high chance to just end up with a hand that you can't work with
They both want big, buff creatures, and reward you nicely for doing so
The longer a game goes on, the more Phyrexian Arena puts you in the lead over your opponents, as youll have access to more options and more resources
Keeping these at hand in a madness deck can help you cast plenty of your cards while also drawing new ones, keeping the cycle going