Yes it is realistic to expect all users to continually make backups of their Google services. Maybe google just hasnt made it easy enough yet... but that is what the goal should be.

Allowed access to banned accounts in "Read-only" mode is ripe for abuse by spammers and phishers who could benefit from still being able to access information in the violating accounts. Its the wrong kind of solution to a problem that really comes down to personal responsibility.

I think most people know deep down the responsible thing to do is have backups of all their important data... the cloud is just making people lazy. And providing a "read-only" access to a banned account will only make people lazier and more apathetic about it. "oh.. no worries.. Googles got my back" But what happens when Google is hacked, or suffers a natural disaster, or other catastrophic failure? It only serves to make the problem worse. Losing your data, to even a wrongfully banned account, is nobody's fault but your own.

There so many more reasons to backup your data before something bad happens, not after.... thats what we should be promoting

Any improvements in exporting data from a Google Account that will make a daily backup actually doable are welcome. But Google should not place all responsibility in the hands of the users, since this inevitable will result in bad user experiences and therefore bad publicity.

Regarding spammers and phishers, these are users violating the law and they of course have no legitimate claims to their account data.