I can only say something to desktop wallet.
1.you already said make it much easier to back up the wallet and Keys.
example You get that File from exporting private Keys but actually You only need that secret to back up ur wallet and Not that private key xyz and other Information. You should make it clear wich information is realy important. To make it Mainstream it needs to be easy and easy to understand for everybody. Most people dont know what to Do After Setup a wallet and to get much more Information After Exporting the Keys can easily confuse People
You should keep it as simple as posibile because the Most People are Not tech People Who understand whats goning on.