Another poster indicated wearing it more than one day would actually hurt other people. You might have a song sung to you or an extra smile. Some CM may hand a small child a balloon, but you're at Disney..
To me, it's sort of like the story of the boy who cryed wolf (Strong analogy perhps,but that's the first well known story I could think of). When just a few folks are wearing buttons then it has meaning. If everyone is wearing buttons to announce something, then it loses all (or most) or it's meaning. It becomes nothing more than noise, and those who are really celebrating thier birthdays or wedding days get treated as if they are just milking it - instead of being treated special.
When buttons were rare, they personally had meaning to ME. I would say good wishes to folks who had honeymoon buttons. Now that everyone has a button, and they are likely wearing it the entire week, it has little meaning to me personally. I'm less inclined say, to encourage (permit) a button wearer go ahead of me in line.
Now, I'll still distinguish if you are on a honeymoon at WDW, that would merit wearing a button all week. I secretly appreciate first timer buttons - cause that lets everyone know they MIGHT need special help (so to speak) navigating around WDW.
but birthdays...well...they just aren't a big deal in my mind. If it's some random anniversay, like 3rd, 12th, or 23rd - one day is plenty. You get up to your 60th anniversary, and yeah - if you are celebrating and both still able to walk around WDW for a week - then you can wear it all week!
Seriously, it's not that big of a deal...but like anything else, the more folks over-use the benefit, the less value it has for everyone. In that sense it does hurt those who actually have a birthday/anniversary/etc. I'm sure the freebie perks have diminished accordingly as well. Instead of real free gifts all you get are a periodic greeting or song.