well i never did a newbie post untill about 6 months after i joined...
but somewhere in my heart i will always be a newbie!
Jiggle
I think it's down to newbies copying what other newbies have done and it's no bad thing IMO. At least it shows they are reading the forums and seeing how they may make a start here. The best newbie intro posts are those that make an effort to tell us about themselves with a well written or thought out post, not just a few lines which says little. It's not mandatory to do a intro post, though it does help. In the long run joining in with the banter is the best approach to putting across personality and is the best way to get known.
LC
I've just posted my second post after almost a year on here. Wish I had done a newbie post when I joined, I probably would have felt more included given how many posts I read despite not posting myself.
A polite , and amusing hello thread can always help to prevent merciless savaging from forum members who are less calm and serene than me . So its a nice thing to do . Also it shows up the 100% numbnuts almost immediately :-)
I haven't done a " Hi, Im new here..." thread - can't see the point. Fair play to those that do, but I think taking time to get known ( having the bonus of talking a titanic amount of bollocks in the process ) is better, but it would be boring if we all thought the same.
:roll: 
Thing is,in my opinion that newbies can get known just as well by erm just posting on other threads!(Less likely to get savaged from the off aswell)