For Fart Apps
and pointless widgets.
You can't write a serious GUI application for every platform without differences in design.
I hate to bang on about this AGAIN
But this is garbage and always has been except for trivial widgets:
" Finally, at long last, developers can use "90 per cent" (its figure) of the same code base to create Universal Windows apps for Windows Phone, RT, desktop Windows and now Xbox."
No you need DIFFERENT GUI and UI strategies for
1: small phone/screen
2: big phone
4: Desktop / laptop etc
5: TV with only a remote
6: Games console with game pad etc/
7: Server, even if GUI as it has to be bandwidth / Remote Access friendly
Underlying non UI related code could be the same in some cases. But writing the SAME non-trivial application for these is fantasy. The same GUI dehydrated death no matter if old idea of miniaturising Win9x for WinCE 320 x 240 or expanding Zune GUI ported to phone up to a desktop.
Sinfofsky was doubly mad forcing one tile GUI yet different APIs.
Obviously APIs to access storage / files / draw primitives / print / communication etc should be the same. But even if EVERY API was identically compatible for the 7 platforms there you'd be moron to port say the same 3D modelling or accounts package with no GUI or design changes. I'd guess a trivial thing like an eBay sniping tool could be a little "widget" the same on all.