The motivation for wearing replicas varies from person to person. For some, it's about impressing other people by giving the impression that you're wearing a Rolex or Panerai. For others it's truly about a love of watches, and an appreciation for the mechanics and design. For most, I would think, it's probably a combination of those two things, with other considerations mixed in there too.
For me, I love watches, but at this point in my life (grad student) I cannot justify the purchase of a genuine watch that I would like. I'm also slightly vain and a brand whore, and I care not so much about giving the impression that I have money as I do about giving the impression that I have style and taste. I find that hard to do as effectively with citizens and seikos. It's also, for me, kind of a form of make believe. I get pretty much the same practical experience of wearing a $5000+ watch for a few hundred bucks. In other words, it's more about fooling myself into a feeling than it is about fooling others. In fact, in situations where I know people will recognize/care about the brand of watch I'm wearing I'm more inclined to wear a citizen.
Finally, re: the argument about homage watches, as far as I can tell replicas offer higher quality, accuracy and value than the available homage offerings. I also feel like homage watches make you just as much of a "faker" as reps, but are much more likely to give other people that impression (because people will know it's an homage, they probably wont know it's a rep).