Highly developed nations in general seem to have very low homicide rates and very low crime rates. The gap between the Netherlands and Singapore is much smaller than the gap between the Netherlands and Russia (20 homicides per 100,000 in 2006).
Sure, low crime rates are one (of many) factors that make for a nice place but they are not the only one. I will take my freedom of speech and the one in two million chance of being mugged and killed in one year in Germany over probably something like a one in four million chance of the same happening to me in Singapore any day.
(We also don’t know whether something like Singapore can scale up to 100 million or 300 million people or whether you can turn a highly developed nation with a population of, say, 100 million in twenty Singapores without unwanted side-effects.)