That's kind of how I feel. I don't need achievements, but when they are there they can be fun. In the old days I used to challenge myself to do crazy things, and achievements just encourage me to keep that up. They encourage you to try things you wouldn't normally do sometimes, and gives you an excuse to replay games. I like them in Civ V because they give you a reason to play all of the different options, so if you're going for achievements you will have played every single civ, you will have made all of the unique units, you will have won every victory type, and so many other interesting things. I'm not heartbroken when a game doesn't have achievements, and not too upset if I don't get 100%.