It does smack a little of paranoia I agree, but in my mind it's a healthy paranoia. It could also be argued however that to view the use of pseudonyms as "sinister" is equally paranoid!
One important point that I think people often forget regarding forums/chatrooms etc is that when a poster uses a real looking name, many other people automatically believe that person is who they say they are. In many cases this is no doubt the truth, but as this is just the virtual world, there is no assurance of that whatsoever. How do I know you're really "Chris Castle"? I don't. At least the use of a pseudonym clears up that issue once and for all. You could say, "well, check out my email address, etc", but as we all know, that's just as easily spoofed as any other online information.
Please don't for a minute that I automatically suspect you of being someone else, but to offer a real example of the above, on one of the other forums I run, there are at least two people who use completely false, but real looking names - I know this, because I know who they really are, but nobody else on the forum does. This is not a problem, it's just another way of using a pseudonym, but in some ways I find it more disturbing than if they just used a handle instead.
To offer a more general example, I have posted to many different forums over the years, and some of these have involved posting regarding topics that would certainly be of interest to an employer, and not in a good way. If I search on a particular pseudonym in Google, then I many of these postings are instantly to hand to any interested parties. If I had used my real name, then my real name would be associated for ever more with those postings, which to my mind is undesirable.
Now, I can see how you'd see this as paranoid, but I currently work for a company that specialises in information gathering on individuals, and although they don't scour the internet for information, it's not outside the realms of possibility that they, or some other interested party might do in the future.
Personally, I think it's desirable to retain as much privacy online as possible, within reason. For someone who really wanted to find out who I am, it wouldn't be very hard just by making a few informed enquiries. To me it's about balance. I want to have a degree of freedom in what I post online, but I don't want to broadcast my name everywhere, nor do I want to be so paranoid that all my online activity is carried out via 10 anonymous proxies, using anonymous isp accounts, etc, etc.
Phew!! All this said, if anyone really is bothered by this, then I'm quite happy to tell them who I am via mail/pm.
I hope I've explained myself here, so please feel free to discuss whatever you want on here.