What I'd like (and I suspect many other developers would too) is a nice laptop that I can install Linux on, and have it Just Work.
What it looks like Dell is providing is a nice laptop, but with a custom build of Ubuntu installed. If Dell's Windows installs are any indication, that means it's going to be loaded with crapware or custom non-OSS drivers. This is just speculation, but the fact that you can't dual-boot Windows on it is a big hint. Who knows what crapware they're going to load up on it, and then you'll be tied to their special brand of Ubuntu if you want upgrades or support.
What Dell should do instead is work with hardware manufacturers to iron out Linux driver bugs for just one nice laptop. Then sell that laptop with a stock Ubuntu build and let developers go to town. I'd pay a lot of money for something like that. Instead, today I have to buy a cheap Dell laptop, install Ubuntu, and deal with the driver headaches that exist to this day. (And don't tell me Linux is a magical fairy land because it Works For You, because it doesn't Just Work for me. It hasn't for years and it still doesn't today.)