so this is a legitimate concern.

As a frequent MTT player, I'd like to see the biggest prizepools possible.

As a site pro, I don't want to see anyone just miss the start of the BIG BTC.

I think the sweetspot for late reg is ~5-15 minutes.  I want to catch the guy that just missed it, but I don't want the guy that just busted re-registering.  Very few players will bust in the first 15 minutes, and those that do should be easy to catch a re-entry under a little-used account.

Certainly things to think about, but IMO late registration will be +EV for the players, as it encourages action.