But didn't Storm Thorgerson make Yes' Going For The One album cover? It has Roger Dean's Yes logo on it. Maybe this was before he made that decision?
I don't think so - pretty sure Storm always had that mentality. I would imagine in the case of GFtO, the band insisted on Storm using their classic Yes logo. And to be honest, on that album, it looks completely out of place.
For DT, the impression I got from MP when discussing DT's album artwork was that the band pretty much lets the artist do what they want, trusting that they know what they're doing (the artists are the professionals in that field), and only vetoing something they (the band) don't like or want changed. Given that they were simply excited to have someone as legendary as Storm doing their artwork for their fourth album, they were probably willing to go along with whatever Storm suggested, hoping that it would help them move up to the next level of success and popularity.