Multi-sig requires infrastructure. It isn't a magic wand that we can
wave to make everyone secure. The protocols and techniques necessary
don't exist yet, and apparently no one has much of an incentive to
create them.

It is starting to happen. If you're OK with using a specific web wallet there's BitGo and greenaddress.it already, though I think their risk analysis is just sending you an SMS code. I wrote up an integration plan for bitcoinj a few days ago:

https://groups.google.com/forum/#!topic/bitcoinj/Uxl-z40OLuQ

but guess what? It's quite complicated. As with all these features.