I see this a lot... well, somewhat often at least- it's not just the Poser community; it's fairly rampant in game mod communities as well. As far as I can tell, it's sort of a status thing- "Hey, lookit me, I released something cool!"... which is why most anyone releases free stuff anyway, apart from genuinely trying to help the community. Still, it boggles the mind that people would release stuff that wasn't actually theirs to try to gain "status"... The only legitimate reason I can think of is the culpurate not understanding that just taking a texture and recoloring it does not actually count as "original work". Apart from that, the only thing that would cause someone to take the credit for someone elses work is a desperate need to feel valuable or some such...

Personally, I'm too damn proud to do anything like that. I guess the people who steal other's work and pass it off as their own have no pride what-so-ever. Rather pathetic if you ask me... sigh