battle.net is fine and I agree withe the others that you are a little paranoid.

have to remember that blizz and its parent company are BUSINESSES. their main goal is to make money and that is what they are doing with this. Plus from a business aspect, what would be easier to maintain? accounts that are linked to b.net and not to b.net? or have all players use b.net?

also about the "hackers" and what not, I am sure they will put up some safeguards in.