I get what you're saying, and if you don't like the idea of it, of course you don't have to post there. If you have a name picked out that you absolutely love and won't change your mind, there's really no reason for it.
But - if you're considering several names, or have some potentials but haven't fallen in love with one yet, it's a good place to screen for bad nicknames you might not have thought of, or associations (for example, apparently in one of the FN + MN combos I love, both names are from Twilight. That might not stop me from using it, but I had no idea, and I'm glad I know now), or to see how the name will be received by a larger audience than just you, DH, and maybe a few friends and family members. Because the kid will have to live with it forever; it will be part of people's first impressions, potential bosses will see it on resumes, etc. For me, it's nice to get a sampling of how the general public will react to the name (or at least the limited sampling that's available on that board).
I've also just always loved names, so for me, it's fun to see what other people are considering.
ETA: That first sentence might sound a little snotty - I didn't mean it that way at all!