People don't have to buy a lot of applications, but applications bought could have different interfaces and behavior when used on laptops vs tablets/phones. Using Skype? The laptop version could include the IM section, but that could be excluded from the tablet/phone interface. Just as an example.
On the phone side, one thing Microsoft has gotten right is the Universal app store. That way, I can run Yelp! - currently available only on the phone OSs - on a tablet or even laptop, w/o opening a browser. Hope it also solves one issue Windows Phone 8.x had - most apps being 'web containers'