While i like the focus on "simpler" (by DT-standarts) songwriting and melody
I like the tightening up of songwriting, but it also kind of shows the weakness of DT. Commercial song arrangements are usually simpler mainly because there is an extremely strong hook and making the song too long dilutes and takes away the focus of that. My main problem with prog is the long songs are kind of a substitution or crutch that hides the lack of legitimate hooks.
I'll give too examples of DT12 on hooks.
I liked The Enemy Inside immediately. To me, the opening pre-vocal intro is the hook and everything (except the bridge) just strongly upholds that hook. It is concise and has a very direct musical style and theme. Really good songwriting (although DT fans don't seem to like this song as much)
I also liked parts of Illumination Theory quite a bit. But the larger concept took away from what could have been strong hooks that stood on their own. Live, Die, Kill could have been a Top 20 song for me on its own. And the Pursuit of Truth had a good hook, but less developed than Live, Die, Kill. So two strong hooks that could have been used to create two more concise, hook driven songs ... weren't.
The rest of the album is kind of not great, not bad for me. Nothing that would even come close to a Top 30 or maybe even Top 50 DT song for me. And I feel it is because they really didn't have a strong hook. They might have had hooks, but not very strong ones.
And yes, a hook is subjective. It isn't like there is a definition that can guarantee parts of songs are universally accepted as a strong hook and others have no hooks. Ultimately, I blame the vocalist as they are usually the songwriter in a band that creates the hook. JP is the main songwriter (by a wide margin it seems), so the hooks are almost always the guitar over the melody. I kind of feel like if DT forced themselves to write the melodies first (not all the time, just mix it in), they'd create a new instant classic.