If dolphins are "closely related to whales and porpoises," orcas are, as well. They aren't whales but they aren't so different as to cause too much confusion.
I'm saying orcas aren't friendly, in general. Animal friendly doesn't always translate to human friendly, especially when the animal lives in the wild and weighs thousands of pounds. Folks can see these things perform but wanting to hug one is a different matter. "Oh look at him playing--oh look at him grabbing my leg--maybe he's just playing--I hope I don't die...."
Besides, killer whales (which is a much more scary name than Orcas) aren't as cute and widely viewed as cuddly as dolphins are.
They are much larger and scary. Dolphins save lives, or so I've heard. I still don't want to be in the water with one. But, I'm more eager to swim with a dolphin than an orca, whale, or shark.