Cheaper, faster, more locked-down and proprietary. Unfortunately most people don't seem to care about the last point.
Then there will be new models from Apple, but you the cycle will repeat itself, again no linux support etc..
http://www.righto.com/2013/09/intel-x86-documentation-has-mo...
The M1 is really the same as an SoC in an iPad/iPhone --- essentially zero public documentation.