Complexity and the evolutionary process are not directly correlated. All living organisms, even placozoa, evolve; it just so happens that modern placozoa have evolved in a manner which did not not favour an increase in complexity (or, perhaps, favoured DEcomplexity).
No, it's true. Evolution is simply a process of adaption to local conditions via the mechanism of reproduction. There is no great cosmic chain of Progress that places placozoa on the bottom and animals which possess "human" characteristics on top - no rule that says evolution WILL create complex life, evolution WILL ONLY raise animals ever closer to gods.
Placozoa have evolved, and continue to evolve, according to the needs of their environment and the whims of the blind watchmaker.
So is this like that slime from Ghostbusters II and that's how they got it to move with the music because it's moving with the music I like that movie.