Bitcoin doesn't solve the trust problem either, since 51% of the hashing power can forge transactions.
That's not a trust problem anymore. It's against their best interest to forge transactions since this will make their stolen btc and especially Asics worthless. I only have to "trust" someone if there is some benefit for him to screw me. (or is not capable)
For example, if there are 20 servers in the pool, and the multi-sig requires 15 votes to move the coins, then you would have to hack 15 of those servers, not just one, to get the coins out of the pool.
It doesn't take much effort to add new 50 servers and get enough relative votes on a pool. By adding just 10 servers you could freeze funds and blackmail people. It's too expensive to run 100 servers for a system that would work on 10 but relativly easy to add 100 for a short period of time. Limiting new servers doesn't work either.
Outside bitcoin it's easy to make contracts and stuff, but since goverments are atm openly stealing funds so that doesn't work here. If they get outlawed, blockchain will still work but these contracts get useless.
It's not as secure as the blockchain itself, but it's certainly a lot more secure than having to trust a single server -- which is mostly what the whole BTC community does with these servers like MtGox and MyBitcoin.
Remember how many btc-services got hacked, frauded, closed, ...
Just because everyone is doing something it doesn't make it right or safe. Online wallets have very limited advantages but huge risks. Nobody has to trust them and everyonw who does with more than change is stupid. I fear that bitcoin will get to big to run your own client and we will have to trust some online wallets. A seperate blockchain would solve that.
What differs my idea from all existing methods is it doesn't require trust or even computer safety. F.e. comparing security of safes with and without insurance and sticking only to mechanical details is pointless, since a shitty safe with a solvent insurance is far safer than Ft.Knox.