Local scout, music search, Bing vision, and Bing related news and tools are accessible through the search button. With IE you get the ability to search and visit websites...not the same at all.
Ah, good point. I was specifically thinking of the Search function, since that is what the button is primarily used for, and that is what the icon on it is.
However, those functions you mention don't appear when clicking that search button, they appear only after multiple other interactions, either swipes or clicks. They are also, IMO, accessory functions that have no place being one of only 3 hardware-designated buttons. They would work much better as simple tiles. For example, Internet Explorer, arguably the most crucial app on the phone after the basic phone functions, is a tile, not a hardware button.
It would be interesting to see how many actually use the additional swipe-screens you can access after the Search screen. I can say that in over a year and a half of owning a Windows Phone, I have used those exactly twice - when I first got the phone to look at them, and now that they were pointed out in this thread.