If you own an iPhone or Android phone what tablet do you buy?
If you have an iPhone and then buy an iPad, most of your iPhone apps will run on the iPad. If you have an Android phone and then buy and Android tablet, most of your phone apps will run on the tablet.
If you buy a Surface, you have to buy all new apps. Since I have neither (iPhone or Android) it doesn't affect me, but many people do (they are the two biggest market share of phones). Will people want to do this?