That salesman is full of shit. Find another dealer who does not lie and/or knows what they are talking about. Just because a vehicle has ABS, it does not automatically have TC. IMHO, traction control is a good feature to have on 400 lb. sportbikes that put out 120hp at the rear wheel, but not nearly as important on a 900 lb. cruiser that puts out 1/3rd less than that. My Ducati has traction control, and it has only engaged once or twice with spirited riding, at full lean, on wet roads.
ABS is an important feature on any street bike.
I live in a state that has lots of snow, dirty roads, and high mountain passes. Traction control can be a lifesaver if you run into an unexpected patch of snow or gravel while on the throttle. And in the rain, especially on dirty roads the rain hasn't washed clean yet. I was riding with a friend last year on a road trip (both of us 2 up) and watched his K1600 start to slide on a patch of dirt, only to be saved by TC.
No doubt, I've been able to ride on the track a lot faster than I normally could thanks to TC, but that is an environment where I am intentionally exceeding the limits of traction exiting corners and relying on TC to bail me out. It's those unintentional times on the street where it can also come into it's own.
Lack of TC didn't stop me from buying an RGU, but it would definitely be a better bike if it had it. That said, you couldn't give me the BMW cruiser, and I've owned a LOT of BMW's, and still ride a GSA. That bike looks like crap, BMW service often sucks, a lot of their bikes are on recall, and BMW could care less about their customers.
The stanction's have failed on GSA's (which is a potentially deadly failure) and I've been waiting for 4 months for BMW to fix mine. Other BMW's have been dealing with other recall issues of their own. They weren't legally allowed to sell a lot of their this year because of recall issues. TC doesn't do you much good if your forks fail.