The Apache license is a wonderful license. If you want to use it, you absolutely should use it.
But people don't use it. They prefer to use something they can understand, something that doesn't have to be interpreted by a legal team, and something that they can feel comfortable imposing on the users of their code.
According to a 2015 survey conducted by Github, MIT and BSD simple licenses are nearly five times more often used than Apache. Out of the top ten most starred open source projects, nine of them use MIT/BSD, and only one uses Apache.
Clearly, there's a desire — in the actual practice of sharing open source — for something that explains your legal and social obligations in as plain an English as we can muster, while still being crystal clear in legal terms.