I luckily never got my account suspended, but I've certainly done some minor violations of the TOS here and there (e.g. in college I downloaded a few copyrighted books and stored them in my Drive for my strictly personal consumption, and I'm sure those files could be fingerprinted and detected by Google, ...).

From what I've heard, when it happens it's not quite easy to regain access, in the best case it takes many days, and the frustrating thing is that there's no support to which you can appeal to, you're mostly left to yourself (e.g. Google employees connections, twitter noise, ...).

I find it silly that my electronic identity would be held hostage in such cases, so with an external domain I can flip a switch and keep receiving my email somewhere else.

I also primarily use a 'flip a switch' setup specifically for this reason. To be honest I think that using your own domain name is the only way to go these days, as even other email providers can have issues resulting in you being completely locked out.

At least with a domain name you have multiple paths for recourse or regaining access should something go wrong (domain registrar, hosting provider, DNS provider, mail provider, etc).

Now that I've moved to Cloudflare Registrar, I guess in some ways I've made it harder for myself should something go wrong, since my domain and DNS are now hosted in the same place.