Now is just the latest round in the browser wars
In the earlier round, netscape made its money by charging businesses and also by selling its web servers (which served up the pages the browser was used to view.)
Microsoft, which had/has a monopoly in the PC industry leveraged this by (among other things) shipping IE free with windows, ensuring windows would work better only with IE (through hidden APIs not available to other browsers), and arm twisting PC Sellers like Dell, Gateway, or even Apple.
By providing specialized features, Microsoft could ensure control, ensure the OS (where they made most of their money) remained the pre-eminent channel for users, promoted other platforms (ActiveX) and MS specific extensions and even got to a point were numerous web pages would only work with IE.
They got called on it by the anti-trust department, lied and were evasive in court, and got away with a slap on the wrist when the government changed.
The rise of the browser as a independent standards compliant platform :
- Makes the choice of OS more irrelevant (ChromeOS!, MS with their first loss ever)
- Promotes related search (Bing/Google with large ad search revenue) and other associated add-ons (accelerators, flash vs silverlight, activeX vs not, ) and technologies.
When mobile phones/tablets become a multi-billion $ business with users consuming web pages, web games, movies via the web, why wouldn’t MS try to control this (or at least have a dog in the race) ?