I've gotta believe that this concierge service is mostly GM's OnStar. I think the biggest surprise for me in the statistic that 43% of the people never use it is that 57% have. Though I guess just trying it out one time to see how it works would no longer qualify you for the "never used it" category.
That would be my guess too. I got a new car recently with an infotainment system, and while it doesn't have any kind of concierge service (thankfully, what a waste; it's a Mazda BTW, which doesn't seem to have this available unlike the domestic brands), it does have an XM radio built in. I got a 3-month free trial subscription with the car, which of course is to get you hooked. So I went ahead and went through the steps to register (without giving them any credit card info of course; that would be a good way to get billed for something you don't want), and went through the trouble of getting it working on the car, mainly so I could try it out to see how it works, and to say that I have. So I've tried it: it has a bunch of stations, they play a bunch of commercials and have DJs yapping a lot, and when music finally does play, the sound quality is absolutely abysmal. I figured some of this would be the case before setting it up, just based on what I've read about XM, but I had to see for myself. Now that I have, when my 3 months is up, there's no way I'm going to actually pay $10/month or whatever for this crappy service.
And I think the monthly (/yearly) payment is definitely a big turn-off for services like this. It's bad enough we need to pay monthly payments for so many other unending services: ISP, cellular, etc., I sure as hell don't want to pay for radio or concierge.
Luckily, unlike your OnStar, my XM radio doesn't waste any space on useless buttons; it's all built into the infotainment system. It shows up under "AM" and "FM" in the device list. But thanks to some hackers, there's patches out there you can pretty easily use to modify the system to reorder these entries (placing XM at the end instead of near the beginning), or even remove ones you don't want.
This system also has BlueTooth so I can connect a phone for use for data, music, etc. You should have gotten a Mazda instead... :-)