As a software engineer, I considered myself fortunate to find a job that allowed travel. Although I tend to travel to middle-of-nowhere places, I enjoy experiencing the local flavor. And there is, usually, some sort of flavor.

It's also a nice benefit if you get to keep your points/miles.

I assume they're sending you because you're good at what you do and can interact with the customer. These two things are great skills to have. My company has two types of devs - ones that should be kept in a cube and ones that can be sent on client visits. Both are vital, the latter are more marketable.