As mentioned before. Warmth, a little more protection. I ride an Ultra with all the lowers and such. Never bought into the chaps theory until a buddy told me to quit being cheap and buy a pair. 45 miles each way to work and I wear them below 60*. Makes a big difference.

 

Anything leather = Fox Creek Leather: Unsurpassed quality and customer service! Buying ONCE is always cheaper in the long run. I have some of their stuff that's going on 8 years in all kinds of weather and still works great.

 

I will add that I have chaps and overpants and most times I will grab the overpants because of easy on/off and more protection.

 

They are great for cooler rides, knocks the wind off, with the right cut you can still get in all pockets with ease. Easy to take off and store.
I saw a lady this past fall pulled over rubbing on a nasty gash on her lower leg, said a piece of gravel flew up from an oncoming trike and struck her. I was wearing my chaps, suggested she may want to try some, may help with this kind of thing. She said she always thought they were something to laugh about, but not anymore.
Hey, some may pose, but when I wear 'em, they are for my benefit.