Its the same as most offices worldwide, there's always somebody that spoils things for most of the other people.
And that would be the irresponsible people at your office, yes?
Bandwidth doesn't come free and company interests come first, yes? If bandwidth is being eaten up with people visiting facebook and webmail sites then something must be done about it, to protect the company and ultimately protect the staff and their jobs. Malicious code can cost companies thousands to eradicate and webmail is one of the most common sources for that code. 25% of our bandwidth (and we're a very large company with a massive internet pipe), is taken up with facebook alone. A huge proportion of all the malicious code that we track down that enters our network, comes in via webmail.
Don't forget you're at work, doing work, not looking after your personal interests.