Great idea. We flew a short way from Sydney to Cairns recently and they basically did this on our flight anyway, so there were about 6 families together and we could all give sympathetic looks. As it was, DS was fine, a bit wriggly but no screaming, but I thought it was a fab idea.
On his very first flight (he was 5 weeks) from Adelaide to Sydney, they put me (was travelling on my own with him) next to a "nervous flyer" who had never flown before, but had 6 children - so she spent the flight helping me, which took her mind off it, and I had a willing and friendly helper.
On the other hand, we flew back to the UK business class with DS, so don't know how that would work.
But in general I would way rather be near other children than someone who smells or is going to wince every time my child makes a noise.