Absolutely! Keyboards add that extra dimension to the music. That's a great list, too. I'm a huge fan of Purple and Steppenwolf, among others.
The Beatles made excellent use of piano in many of their songs, as did Lennon and McCartney when they continued their solo careers.
The Moody Blues were one of the early bands to use keyboards in their fusion of rock-classical music, and their concept album, Days of Future Passed.
But Jon Lord really brought the organ to the forefront with DP that put the "heavy" into rock music. He was a master musician to begin with, and the organ solos and his cross-work with Ritchie Blackmore's guitar, really defined Purple's music and set them apart from other heavy rock bands of the day. As keyboards expanded, Lord incorporated them into his set up.
You might add Santana to your list, also. Great use of keyboards with guitar in his music.
“Music can change the world, because music can change people.” Bono