but, if the recovery seed uses common words aren't they very easy for some one to guess and 'recover' the keys even without touching your device? they could just guess all combos?
http://www.bitcointrezor.com/faq/#how-can-seed-made-several-simple-words-be-more-secthis in a point of sale at the shops
Trezor is primary bitcoin *safe*, not mobile wallet for spending coins in bar. Wallet for change money don't need to be as secure, because people usually don't take all their lifetime savings to bar.
I believe there's no need for custom bitcoin mobile wallet, because everybody will soon have smartphone or other general purpose device which will be able to keep small amounts of bitcoin.