I would think the theft problems are not what they used to be. GPS units used to be pretty expensive just a few years ago, but that's not the case now. Most consumer units are under $200 retail, some are under $100.... and they are common as peanut butter. If they are still a hot theft item, I may have to start hiding mine again, even though it's probably not worth the cost of a map update. lol
I like having the standalone GPS unit. I don't want to pay a premium to build something into the car if I don't have to. What if you trade up to a new car in a couple years? What if you own more than one vehicle? I would rather have one nice GPS to keep with me no matter what car I'm in. The power cord can normally be run neatly without being in the way or "unsightly", with a little effort. Besides, I like having my GPS located up at the windshield where I'm looking. In the CX5, I put mine to the left of the steering wheel, over the front dash speaker.... works really good for me. Cord is run across the seam of the dash, and down to the 12v... with a clipped in place at the center a/c vent.
Besides all that, there are times I prefer to use google maps on my phone, etc. I don't need technologies built into the car that may be outdated before the warranty is up. When I bought my 06 Mazda5, they had a $2000 nav system option. Holy crap, what a waste that would have been... zero return on investment and dollars down the drain. I wonder if anyone actually uses a bulit in nav on a car that's 5+ years old?
What I really like about Mazda's nav option is that it's not their own stupid map program, and the cost is reasonable... cheaper than I expected and it does make it tempting. It's genius to use a brand name GPS system, so you get a real competitive product. I'm not sure if other mfgs are doing this, but it's the only way I would consider paying extra to have it.