I'm in a similar situation because my in-laws aren't coming to our DW. They aren't afraid to fly, but rather don't like to fly. This has definitely caused some upset, especially for my FI (even though he doesn't always express it).
I think that every couple needs to decide what is most important to them. Although we would love for his parents to be present, we want a DW and want to enjoy each other on our day. As for our guests.......we are happy that they WANT to be there for us and have taken holidays, spent $$, and are making the effort.
I'm sure in the long-term this will affect his parents more because they will be missing out on a very special moment.