All the problems mentioned with the vault aside, I like that the current system will eventually change because it is rather flawed.
However, if you want to get rid of alt-vaults, why not just remove alts? There are no skills that you can get as one character that you can't get as another, so its not like you need multiple characters.
Also, the whole ability to steal from a hearthfire seems problematic. I don't really like how people can be summoned while offline right now, and the whole idea of being stolen from or killed without any ability to defend yourself seems pretty harsh.
I do like the lock and lockpick idea. When I purchased locks & bolts to make a cellar, and found out cellars could neither be locked or bolted, I was dumbfounded. While a certain amount of un-intuitiveness is expected in an alpha, that borders on fraud.