How the heck is a ballot going to tell anyone anything? Whatever the default is is what will be selected most of the time. Windows includes an internet browser so you can go figure out what internet browser you want by reading reviews or whatnot. If you don't know how to do that, you don't care about doing that, and IE is good enough for you.
If anyone writes it at all, someone will be able to take fault with it. One company or the other will wonder why then ended up getting the pros and cons they did.
Windows ships with an internet browser that lets any user download the internet browser they choose. They can read the reviews they want, from sources they trust. Nothing in Windows stops users from doing this. IE doesn't crash when you go to download Firefox.
With changing software, pros and cons may shift over time. Does Microsoft have to update its installer? There is no way the EU can pull this off and make any sense at the same time.