It's not supposed to be a good idea. It's Microsoft trying to make the EU regulators look stupid. They will take the blame for this despite them preferring to have competing browsers available from a first run menu.
Microsoft clearly believes that a simple choice would be bad for them so they're making it so that a) the consumer who buys an OS has to go out and get a browser, and they're hoping Internet Explorer will get greater share than otherwise, and more importantly b) the OEMs will, in the main, install IE and only IE which has much more effect as that is how 95% of people get their OS, with a new machine purchase.
Microsoft clearly believes that a simple choice would be bad for them so they're making it so that a) the consumer who buys an OS has to go out and get a browser, and they're hoping Internet Explorer will get greater share than otherwise, and more importantly b) the OEMs will, in the main, install IE and only IE which has much more effect as that is how 95% of people get their OS, with a new machine purchase.