I'd agree that there's a degree of subjectivity in this: my wife shudders every time she sees a hairless cat, but I think they look cool. Not pretty, mind you, but kinda badass.
At the same time, there's a degree of commonality in what we find pretty in things, ball pythons included, and that's where I'm coming from asking about the appearances in this context. If you combine eight morphs and end up with a dingy yellow snake or something like that, I think most people would agree that wasn't really a great combination in terms of the looks you get for the breeding that went into it. As Darkbird said, if you have so many morphs in the snake that you can't really tell what it has anymore, what's the point? I'd imagine that with many combinations there'd be a point where you wouldn't be able to tell whether certain individual morphs were even present because they wouldn't appreciably alter the appearance. The only way to find out would be through breeding and (hopefully) getting a baby with that single morph.
I also agree that a highly complicated snake like that would most certainly be of interest to breeders only. Considering the value of the snake it's unlikely someone would pay that price tag for a pet snake. So in that respect the appearance would be a bit less important considering the breeder would find the biggest value in the likely less-complicated offspring that would likely be bred. A six co-dom morph combo would have a 1/64 chance of producing normal offspring bred to a normal morph. Roughly half the offspring should be 3+ morphs... that's good odds.
So what I'm getting is that the main drawback to breeding massively complicated morph combinations is that as you increase the number of morphs in a snake you can make it more difficult to tell what morphs are or aren't present in the snake (and any similarly complex offspring) without breeding them out to prove each uncertain morph.