Why would anyone trust something that can spawn all of your private keys ever out of nowhere? Im still using the old wallet.dat format because im paranoid of the HD format of the new wallet.dat, imagine if I had to trust any of these brainwallets. Why expect your seed isn't going to eventually get bruteforced?

I personally feel safer by holding private keys locally which could never be accessed unless you actually had access to the files and you could always host your file somewhere in an encrypted SHA512 file with a strong password or something, if you really needed to for example move somewhere without carrying your private keys physically.

I just don't like the idea of "you need a couple of data here and there to derive all of you private keys", doesn't sound like a strong model to trust.