Don’t dismiss the need so easily. I would also pay for such a box for my laptop!
There’s a ton of uses, but the most obvious one is portability… travel to a conference to give a talk, you can demo on your laptop.
Same with traveling to a client or demoing at a studio, whatever.
What’s the alternative? Lug your own tower around and hook it all up for a 5 minute demo?
Or intrude on someones machine at the site and hope it has the right hardware, and use time to install drivers and software?
And in fact I use my laptop for CUDA development all the time and I would pay serious $ to get some G200 support, including plugging in an external box like this.
Sure for your desktop machine, buy a card, but actually this kind of hardware innovation is exactly what will make GPU computing easier and more ubiquitous.