People buy alienware mostly because they don't know what they're doing. People buy looks, too. But if someone sees "Oh this PC is faster than this one" that matters to a end user, and thats where the SSD comes in. It just helps sell an item, at least from what i've seen. Also, the 370 is a very good card for $140, 1080P in a lot of games at around 45FPS. Hell my 7870 still does VERY well in games. Now, yes, the 380 would be better, but this can be sold as "entry level, you can ask for more!" Or take some stuff away and make someone pay extra for a SSD, a better case, or what have you.
I would just like to add, a PC similar to that is what I've built a few times for people by offering the building service off craigslist. The only difference was they gave me a price and what they wanted to do and I would build around that. So it was mostly GPU changes, no SSD, bigger SSD, and so on. So this is just off my experience in a unofficial business.