I'll also agree that anyone should go about their wedding as they see fit and that includes a "no-kids policy". I think what knapp and myself are saying is that realistically, a "no-kids policy" is going to be tricky to put in place. For example, I could insist on the only music at my wedding will come from a live metal band... and the wife-to-be could agree too. We could do that because it's our big day and no one else's. However, unless most guests aren't averse to getting stuck in a moshpit, this is going to put off a lot of people from ever wanting to come. The people that I'd want at my big day are more important to me than the metal and (unfortunately) I'd have to get a DJ who would play less erm, abrasive music and tunes that are more suited to dance to.
I just see a "no-kids policy" being a more complex situation than some people here think. Likewise, people are usually more complex than they are straightforward. They're probably aware your intentions are good and they understand that. Deep down inside, some parents will just feel more naturally defensive than others about their kids not being allowed into an event, hosted by someone they hold in high regard, or maybe view as family even. They might not show those feelings right away, but those feelings might internalize and they might change the perception of you over time, if not, right now or in the immediate future. Just sayin', but I wish you kids luck anyway in planning out your big day (no pun intended).
On a side note, my dream wedding would be just me and my bride in say, Bora Bora or some island resort in the South Pacific. It would be a wedding and a honeymoon rolled into one, less expensive perhaps (no big ceremony) and a lot less hassle too.