I'm excited for the game, but I understand your position -- I don't like it either. The effect is lessened a bit, for me, by remembering that it's just the one guy doing all of this.
Plus, we don't know that the sounds/tileset aren't just placeholders to allow him to release the trailer's vertical slice! I appreciate that this is unlikely, but still! What we recognize as normal development practices don't necessarily apply to a studio of one.