What has happened (which is the case of pretty much every demonstration) is that peoples attention were drawn to a 'problem'.
Many people have no idea where Sri Lanka is or what the problems are over there. There will be some people who are now aware of the plight of the Tamils there.
Just so that you are aware, 70,000 people have died there in the last 25 years.
http://news.bbc.co.uk/1/hi/world/south_asia/78 28858.stm Maybe not as bad as the Jews in the second world war, but pretty bad none the less.
These protests are similar to any protest that you can name in the last few years - the G20, the Fathers for Justice, the Anti War protesters etc.
They are all marching to have their voice heard and to draw attention to their protests.
Still, it would be far better to make it illegal to hold protests so that you can not be late for work wouldn't it?
*I should also note that my parents are Tamils from Sri Lanka who came over in the 1950s - not to escape from any problems but because the British government wanted immigration at the time. A lot of other Sri Lankan people came over at the time and are sympathetic to the Tamil's plight - in a similar way I guess to Irish Americans in Boston. I point this out as you seem to be under the assumption that all the protesters were refugees