It's just way too expensive and overwhelming to buy mooncakes for everyone and end up with a whole pile of mooncakes given to us that we'll never finish because they're insanely sweet (comparable to baklava sweet) and we couldn't eat very much at a time anyway. We buy one or two boxes for family and let the rest be from gifts that we're given. In our circle of friends, practicality and not having perfectly good food go to waste is a bigger concern for everyone, so we don't mind being given a gift that has been passed around.
It's just 意思意思, a token of respect and remembrance.
They were originally from http://www.eatworld.org (and have since disappeared after I saved the pics), but that site is dog slow for me and I couldn't read to actually find the feature on the site.