Back when I was in consulting, I used to think of it as a perk (as did many of my peers). Once the travel started to wear on my personal life, I ran the numbers and discovered the miles and points I was earning equated to only around $200-300 per month in cash equivalent value.

It's really surprising to me how intensely some people will pursue relatively worthless airline miles. I suppose if you're going to be traveling anyway, you might as well pick them up. But if you have the choice, it's not really worth the trade-off.