I thought Dthrow could be teched right in front of Sonic, and Usmash is hardly good for ledgeguarding. It spikes BEHIND him and if they see it coming it might not even spike at all with DI. Dthrow is a safe option on the ground, but counterteching it and also the fact that shieldstun is higher so running shieldgrabs don't always work, make Usmash have some uses against aerials that Dthrow does not. Grab for punishing and shields, Usmash for aerials.
Dsmash was made too fast in one beta, and was slowed down in the next build. I didn't want a spammable smash, just a more usable kill move to techchase with. I think it still differentiates well with Fsmash. Its more punishable and kills later but has more setups for it. Its definitely not guaranteed, and serves the same purpose a buffed Nair would except it is punishable. If Nair was buffed it would be used to techchase kill instead of Dsmash, and you would have to be far less committed to it. Dsmash is in no way a move to be "thrown out."
Making use of these moves still takes some smarts. Sonic still lacks good reliable kill moves. His throws don't lead into kills with good DI and he just doesn't combo well into them either. Off-stage he has freedom, but still lacks priority to make use of it against certain chars. Those certain chars are also still horrible matchups for him stopping his approach. Usmash kind of helps with approaching, and Dsmash techchasing kind of helps reward that approach, but they're both still punishable and if they aren't I think we intend them to be. Imo theres no need to overreact just because Sonic has good options now. Making use of what you have in a smart way doesn't mean hes all of the sudden an easy character that rewards reckless players, especially not at a high level of play.
Good options expand your tools to work with so you can use them smartly. Too many people think that streamlining something is anti-competitive, and think too much about the worst situations. We didn't really change the flavor of the character directly, Brawl+ just brought global changes that unlocked new potential strategies for Sonic that was always in his moveset. The new buffs should adapt to that.