This rule has become more of a joke than to purposefully encourage pornography of anything.
Be it weird looking trees or fruit, it is not that we find those things sexually attractive, but that they are funny in a sexual context.
It depends on the amount of sexuality presented in the Probopass image you saw, it could be drawn just for the sake of fulfilling the rule; that there must be a porn of everything including Probopass. Or if its drawn in a way that transforms Probopass into an extremely sexualised form, to be seen purely as fapping material.
Just because they're sentient doesn't mean that they're human.
A very good point! However, I don't think that's the idea they were trying to convey. When you boil it all down, I think the current argument could be summarized to a single, opinion-based question. "What do you consider a 'person'?"
When you boil it all down, highly intelligent pokemon are just humans with a different shape, language, and fashion sense, and maybe a few instinctual quirks. Take that as you will, but this is what the arguments taking place here seem to nudge towards... and it's never going to be resolved, because the core question being asked has an answer that's a matter of opinion.
rule 34 exists because we all have fictional characters we find hawt. it may lead to some silly ideas like tetris blocks but the fact it gives us characters like april o'neil,lara croft,tifa lock hart,millia maxwell makes it worth having the rule
You either die a hero or live long enough to see yourself become a villain. http://www.youtube.com/watch?v=CfDtJvYrFD4