First of all, this actually isn't true. You can catch the opponent off-guard by performing a quick maneuver like FF (AD, if necessary)/Spot-dodge/roll > utilt. The FF > utilt, in particular, is VERY effective because of how fast DDD falls. At this point, the maneuver goes from the opponent "making a mistake or rolling into you" to you simply outplaying your opponent through reads and mix-ups. Sure, if all opponents were smarter/had more common sense, utilt would be a lot less effective, but it would still be a useful kill move in many scenarios (assuming the DDD knows how to use his traits in mix-ups).
Secondly, even if what you said is true, basically half the game is just making/taking advantage of mistakes and rolls. This is Brawl. Defensive play is the name of the game. Falco
is going to try to Phantasm through you sometimes if you corner him. If you read that, you get a free utilt. Yes, the Falco essentially "made a mistake", but it's a reasonable one that can be expected to happen during some matches because of how the MU works. Same thing goes for Fox Illusion, Snake's DACUS, etc. DDD is a read-heavy character. If you're playing him, then you have to be able to catch those mistakes and thus land utilts or grabs or bairs or whatever action you have lined up to punish said mistakes. One of the reasons DDD is a High Tier character is
not because he gets 'free' stuff, but because the severity of a punish from one of his reads is unusually large.
You're going to have to show me a video example of you or someone else utilizing this strat you're mentioning to kill someone at such low %'s. As I'm understanding your wording, it seems like you're nailing your opponent with a read (of his drifting AD) that gets him killed (because he's) near a blastzone. That makes Waddle Dee Toss neither "reliable" nor an actual "kill move", since lots of attacks can achieve similar results with similar reads
near a blastzone. In addition, you admitted yourself that "this situation rarely occurs outside of Peach and spacies." That hardly makes this move "practical" overall, since it applies only to specific scenarios in a few select MUs. In general, I can see how Waddle Dees/Doos could be useful in the regard that you are stating, but I don't think that makes them 'better' or 'more practical' than his
established kill moves.
I surmise that you must not do so well against Diddy...
Hello all you Dededes!
I've won almost impossible matches against MKs because of that one mix-up taking it home for me at least once a match. I'd like to know what good Diddys you've played against that allowed you to think that Waddles at neutral were "horrible". 
