Doesn't boggle my mind. "Prog" =/= progressive/experimental. It's a genre, and genres come with expectations, motifs, and staples. People who are fans of a genre will cry foul when its borders have been breached.
That said, while the change in direction is expected and rational, I don't have to like it. I would only go so far as to say that a return to Odyssey-style music would be an improvement vector. It isn't, in my opinion, the only or the most potent improvement vector. A new direction, experimental, progressive - would really transport the band to currency.
I'm not impressed with the modern metal sound of the last two albums as it feels too cliche, too safe, and too unoriginal, however well executed.