For me, when I upgraded to 17.5" wheels (
link), it came down to spacing between the tires. My 16" tires were extremely close- like < 2" of space between them. To upgrade to a better 16" tire meant a larger outer diameter than what I had and I just wasn't willing to risk putting the tires so close together. By going up to a 17.5" wheel, you have a lower sidewall height and therefore, a smaller outer diameter. I actually increased my space between tires.
If that's not a concern, maybe you'd like the shorter sidewall of the 17.5" tires. They do seem to roll on themselves less this way.
