Imagine if you faced fines or jailtime if a criminal simply used your product. Let's say I run a McDonalds, and a drug dealer buys a burger from me, then all of I sudden I helped them launder money? Because that's what 'laundering' money really is, simply the legitimizing of illegitimate funds. HSBC is simply being extorted by the US because somewhere along the line a criminal used a bank account (and of course HSBC is one of the most international of all banks, and operates in many countries where law enforcement is poor at best). If every business that ever aided a criminal, or ever did business with a criminal were prosecuted, there wouldn't be any businesses left.
Plenty of you buy and sell bitcoins, imagine if you were prosecuted because your bitcoins where once used to buy drugs? How would you feel then? (and this is actually a fairly probable outcome)
Admissions of guilt on HSBC's part? Doesn't mean they're guilty, only means they plead guilty to avoid worse prosecution/extortion...
Edit - furthermore, I find it hilarious that people will rail against the NSA and American surveillance, yet call for the heads of HSBC execs for not spying on and policing their clients enough...