I agree with you to an extent however the "block" button is never really an answer. If you were a Troll then chances are the 'Block' button is more of an achievement of 'winning' in their eyes. It can be useful at times however is not the solution to a wider issue.
One person blocks a troll and they move on to the next person they can find its the very definition of a troll. Where I feel that there should be some form of legal proceedings is when the troll is doing nothing more than harrasing, homophobic, racist in a clearly malicious manner etc. Some things may be deemed as unpleasant by one but cause extreme mental distress in others.
A film I would HIGHLY recommend to anyone using any 'social' media would be Cyberbully - http://en.wikipedia.org/wiki/Cyberbully_(film)+Shaun L
the media have always been praying on the 'big stories' and this is very clear by the original article piece. What I hate to see is that the media doesn't care about the cause until after the effect has already happened.
For people who may think that it is ok to bully (even in the smallest way) may like to see these statistics from bullying statistics http://www.bullyingstatistics.org/content/bullying-and-suicide.html
although the statistics may be dated by one or two years it shows a clear issue with bullying as a whole. To which many of these so called Trolls will undoubtedly have an effect on, since children and adolescents communicate as much in social media as they do in 'real world' communication. They also view their online status just as much as their offline status.