I don't know anyone (well, now _you_, but I cannot say I really know you ;-) ) whose bank account has been frozen...
Really? I guarantee that if you ask everyone you know if they've ever had some kind of serious problem with a bank or payment processor, you will hear some sad stories. If not, you obviously don't know very many people.
...and, while it's very inconvenient, detractors would argue that with Bitcoin people would say "All my wealth has been stolen by a malware/antivirus_bug/moths/whathever and I can do *nothing* to recover it".
Not everybody has to store their bitcoins on their computer. Secure hardware wallets are under development to address precisely this concern. Or people can trust a third party service such as an e-wallet to handle their bitcoins, preferably with someone to sue if things go wrong.
And why do you think that you can get the same (or better) service that the existing ones for less than a 3% fee?
Because I
can, if the service is simply "I give you the money and you give me the goods". Many stores will actually offer a discount on big-ticket items if you pay in cash, simply because it avoids them having to pass the payment processing costs onto you, the consumer.
You talk about __trust__ merchants... Isn't the whole point of Bitcoin not to trust anybody?
No, the point is that you don't have to trust anyone other than the person you're doing business with. You don't have to trust the bank not to freeze your account, you don't have to trust the payment processor not to reverse the transaction, you only have to trust that the person you're giving your money to will hold up their end of the bargain, exactly as if you had used cash. And really, isn't that the way it should be?