Like I said...it doesn't ruin my day by any means, and it doesn't rile me up the way many of you get riled up by seeing people on scooters. I just find it somewhat annoying and very unnecessary.
Abbreviating Mickey's Not So Scary Halloween Party or Pirates of the Caribbean makes alot more sense because it saves a heck of alot more characters to abbreviate them. However, saying "DS" instead of "my son" doesn't really save all that much on either time or characters. Characterwise, it saves a whopping 4 characters (including the space). And by the time you stop to push down on the "shift" button to capitalize the letters, you're really not saving yourself any effort in not spelling it out. It's kind of like spending a nickel to save a penny.
I'm not totally opposed to abbreviations. They have their place. I admit that when I'm talking about certain attractions, such as the ones you mentioned, it is more convenient to abbreviate. But some things just aren't worth it. If it's gonna make someone have to stop and think what the heck it is that I am abbreviating, I may as well just spell it out. Such as "SM". Am I talking about Space Mountain or Splash Mountain? I may as well just spell it out, for clarity's sake, especially since it doesn't really take much more effort on my part just to write out the silly thing.