While I think this will ensure you have the full control of your account, saving your key phrase into something that is easily accessible using the internet connection is a bad idea. All hackers now need is to have your Google account and your password to access your Google drive and cloud.
hackers cant hack your google account as well as icloud too easily because both have solid security encryptions . this idea is actually nice because we know dont need to copy our seeds manually , instead we can now just export it to a cloud storage for ease of access .
Why would you use online wallet and online exchange ? Thats more worst because you are entrusting your account to some one else . what if they will hack ? Google and apple have a higher and better security than those who were in online wallets and exchanges . so dont under estimate them because they are in the industry for many years before crypto invented .