For example, take politics. One presidential candidate may be just what you were looking for as far as managing the economy, but he or she may be a bit rigid on social issues. Then there is a candidate who might share your cultural ideas but whose views on the economy may be considered 19th century at best. Seems like you can't always get what you want.
Motorcycles are much the same.
As soon as you find a bike that you believe is your your personal Holy Grail, you notice that while it excels in some areas in others it lacks, if not outright sucks. A great sportbike on the racetrack is often miserable on the street, and don't you dare think about commuting on it. Then there is the bike that has all the ingredients to make a world-class tourer is terrible in the twisties and at track day. Indeed, you can't always get what you want. But if you try sometimes, you just might find, you get what you need.