Sri Lankan here ... agree with most things here, and definitely not the part where Cassandra states there are lots of "unkempt homeless kids, drug addicts etc". I think you might have seen things and took some of them out of context. I can assure you that type of thing isn't as bad as you make it sound.
Law and order here has been going down - but the economy going up (partly due to massive investments after the end of a 30 year civil war). But with that there has been a widening of the rich-poor divide because the CoL is going up and the massive investments are mostly enjoyed by people who already had money or are part of the government and are making money because they control all policies. Now there's a little bit of that investment that is trickled down to benefit people (like creation of jobs, infrastructure, which are good things).
Most Sri Lankans don't care about the corrupt-commission based loss of national wealth - because with all the commission grabbing, we do get some infrastructure built (even though they may seem like white elephants, the private sector is working with it instead of being too negative about these development projects - the tourism industry for instance is gaining from it and so are every day Sri Lankans who are now able to go to places in 2 hours or so that used to take 5 or 6).
If any of this surprises you imagine it from the point of view of a people who have been in a 30 year state of conflict and haven't really had anything going for them apart from the usual political crap (which doesn't seem to cease no matter what happens).
But what we do care about is the loss of law and order people are aware of this. Like what the OP mentioned about some guy aligned with the government, an outright thug, who killed a British Aid Worker and assaulted his friend, who were both on Holiday here, or the case where one of our national ministers tied a guy to a tree on national TV (yup, that's right), or how two national politicians shot each other in broad day light with one of them dying on the spot and the other being shot through the middle of his skull, who survived - and is yet to be put on trial properly - who is also a known drug peddler and money launderer, or the numerous people we read about in the newspapers who are aligned with the government who get away with molesting kids, murder etc, or our chief justice being evicted from her post without a fair inquiry and instead at said inquiry she gets ridiculed in a misogynistic manner by government ministers, and the list goes on....
There has also been a sudden surge of anti-islamic fervour coming from a politically backed sangha (I shouldn't be calling them that really). I'm not surprised, when the Brits invaded us they divided and conquered, and I guess that never really went away - only the people conquering changed shades. Even after a 30 year civil war, it seems that our politicians are used to staying in power by giving the majority sinhalese an enemy to fear at home or abroad.
However, that said, there is also a geo-political thing going on with the USA, India and China that doesn't really help things - although one can argue that it can also be a good thing.
But as far as the everyday-sane Sri Lankan of whatever race or creed feels: we just want to live in peace and don't really have any better options at the moment, and everyone who has an interest in us aren't really interested in us - but something else that they want - be it the internal politics of our neighbour India, a rising China or the investment portfolios of some corporation looking for that next investment or our very own who are more interested in being in power for either power itself or simply to line their pockets with more.
Now add to this people being brainwashed left-right and center all over the place for some cause and you have the potential to ignite a very big fire here (again) - which makes some realists think that we might as well be better off with a dictator, or these people just might actually end up killing each and every one of us (in which case I'm out of here). Hopefully, things will improve with time. Oh one last thing - there's only an illusion of a two-party democracy here - as it is, we are moving more and more towards a one-party dictatorship. Hopefully, at the very least, it's not going to be a one family dictatorship.