#2. They can focus completely on the TV audience

A usual live WWE TV show - Raw, SmackDown, NXT, whatever - always has two distinct audiences it needs to connect with. The live crowd in attendance and the viewers at home. Obviously, I'm not telling you anything you don't already know. I'm trying to make a point. Can I finish? Thank you.
Because of this, there has to be a balancing act between the two. A TV broadcast, for example, has to occasionally go to a commercial break, leaving the performers to have to stall somewhat for at least two minutes until the live show comes back on the air. Even a taped show like 205 Live (that's still on the air, right?) has to take into account the arena crowd, as their reaction to the performers is a major part of the show they're presenting.
Essentially, a typical pro wrestling show revolves around matches that are taking place in front of a live audience. Taped or live, that audience needs to be taken into account in the presentation. After all, that's the entire concept. Or, as Hollywood screenwriter and terrible human being Max Landis put it in his Wrestling Isn't Wrestling short, pro wrestling is a "TV show about a wrestling show."
You take that crowd away, and you're left with a wrestling show - albeit, with the same kayfabe trappings that come with the business either way.
I know WrestleMania is the biggest show of the year (usually), but these are unusual times and it's fascinating that the removal of simply one element - the live crowd - opens up a ton of possibilities to experiment with.
WWE made several mistakes with Money in the Bank?