Asterisks on password entry (or even unixesque blind password entry) exists purely because someone might be looking over your shoulder - on my home PC I'd pretty much like an option to remove them... On a mobile device those are useful because you cannot control your environment and you never know who is looking over your shoulder.

Password storage is a whole different thing - it exists because of convenience (not having to type passwords whenever you want to connect to some service). If you want to implement some security measures there - you have to give up on the convenience, as simple as that.