Internet Explorer is a compatibility solution. It is there to run the old stuff. It is still kept secure but it is not getting any new features, there is Edge for that.

The statistics you quote are meaningless. Go to another statistics provider and you will get different stats again. Include mobile and Safari suddenly becomes rather major.

Supporting a depreciated browser is not the way to go. This has to be understood, the methodology of where the stats comes from is also mysterious, given how much of he internet is click fraud bots who knows what is what?

Heavily depends on your target market, neither does it just hurt to say "This browser is unsupported for being too outdated" we do it for <noscript> why not <nopropercss> :/