#1. The WWE Title picture is wide open right now

The problem with The Miz cashing in right now is that WWE already has a very enticing title picture. It doesn't really need him right now. WWE seems to have a variety of title contenders to choose from. So there's no need to do a cash-in. If The Miz actually cashed in on Drew McIntyre or AJ Styles, it would feel like a cheap way to surprise the fans.
Did you know a top WWE Superstar just wrestled outside the company? More details HERE
A Miz cash-in would also eliminate WWE's out card. With the Money in the Bank contract, WWE could call on The Miz any time they wish. This flexibility is crucial for the company heading into 2021. WWE is heading into a very uncertain WrestleMania season.
There are various variables at play. For now, that's why WWE needs to keep The Miz on standby. He needs to be built up as a better heel in the coming months. In doing so, WWE would still have an out if they opt to call on it. Until then, WWE should let the title picture naturally play out.