EVH's impact, and inclusion as one of the greats, isn't just about raw skill. (which is kinda subjective anyways, as this very thread proves)
It's about impact to the music scene, and the art at large.
He changed the way folks played guitar. He was a big part of the transition in popular music during that time, and he influenced a great many artists after.
His tone was much emulated, as were his techniques. You don't have to like his playing to recognize that impact.