That tiny start buttons and menus are not that tiny, if you have a monitor in front of you. They are tiny only if your real dpi and the dpi that the apps expect do not match. And on the contrary, the controls became huge, wasting ton of space in the Metro/Modern versions.

Metro tiles are OK for simple apps, but you are not going to make CAD or NLE with that. For these apps, you need those tiny controls, ability to cram lot of them into small space and ability to adjust the design to the target intent. Metro tiles won't help you with that.