> I wonder why the Linux distros are so slow to adapt to tablets.
Tight hardware integration. Most tablets have locked-down bootloaders that make it difficult to replace the default OS.
You've also pretty much got to start over when it comes to drivers. Linux used to have terrible driver support back in the day -- I remember carefully choosing motherboards and laptops because I wanted a Linux-compatible chipset -- those days are over on the desktop (except for a few esoteric peripherals), but it's going to hit hard on mobile. Imagine booting your tablet onto Linux but not being able to use the GPS or some other piece of connectivity.
And then, you've got to take all your established GUI code and throw it in the trash and start over. Nothing from the desktop world is going to be usable in a touch environment. The big desktop environments all have heritage going back to the late '90s. You can still see some KDE 1 and GNOME 1 layouts used in their modern KDE Applications and GNOME 3 descendants, and the stuff that was replaced was replaced one app at a time. Throwing everything out and starting over is harder than it looks.
But, still, we've got some attempts at this. Look at Ubuntu Touch, Sailfish, and Plasma Active, for example. In the past, we had Maemo 5, which was amazing, and it was everything I wanted in a touch-based Linux distro, but the only company that had pockets deep enough to fund its development turned away from the platform, and the closest thing it has to a successor (Sailfish) has been a disappointment. Also, even that required the distro developer be an established hardware manufacturer: Maemo 5 couldn't have worked if it was just an OS that could only be installed on third-party devices.