I'm just brainstorming, but I think a good feature would be the OPTION to link a wallet to an e-mail account, mobile phone etc., which would get a key or something required to issue transactions.
On it's face it sounds smart - but digging a bit deeper shows a flaw; if one can recover password or pass-phrases through the email, then the emails' password becomes the weak point especially since it is usually a lot shorter and less complex on top of being on well-known servers (mail servers) that some hackers already know how to enter to.
However, if there's a way to add it just as another layer without any way for it to act as a double edged sword, you might be right.