Lose your keys, you’re out of luck and locked out of who knows how many applications permanently.
It might be fine for us, but just think of the less technically inclined folks in your life. Are they going to remember a 32 word phrase or use a password manager for a key?
And what happens if they’re hacked? If google detects your account is hacked, you may be able to salvage it.
If someone nabs your wallet, they get access to however many apps you have set up along with whatever funds you have in there.