Did they not take risks in the last album by challenging themselves to write concise songs?
No, they didn't.
The problem with Dream Theater and their fanbase is the fanbase's definition of "safe" songwriting. Most of us seem to be completely okay with long instrumentals during a bridge between 2 choruses and the end of a song. Others like the songs where they do less of that. It's not really risky at all to write shorter songs, and to be completely honest, shorter songs in general will always be "safer", if Dream Theater is writing them. The length of a song means nothing in how popular it will be among the Dream Theater fanbase, however drawing new fans in is probably always going to be easier with shorter songs.
It's risky of them to not write music like they've been writing. See, even though they've got cool time signature changes and noodly instrumental sections, the structure of their songs is really never complicated.
They might as well just be composers of virtuosic pop songs. ----Verse Chorus Verse Chorus Bridge (insert long instrumental section so the song is longer than 10 minutes) Chorus---- is still the structure for 90% of their songs. The songs that avoid that are their epics, instrumentals, and some of the songs on SFAM. That's basically it.
To be completely honest, the band isn't really that risky at all. I would
like to see them write something risky, like a standalone mellow instrumental, a song written in a complex structure like sonata-allegro form (not necessarily instrumental), something atonal (because why the hell not), greater usage of other instruments besides keyboard, drum, bass, vocals, and guitar (like some actual real orchestral instruments played by other people, I would totally dig a bassoon or contrabass solo in a mellow section of an instrumental). People have talked about jazz fusion, why not have them make some actual jazz? That's risky. Let an entire song be a Jordan solo (there's too much unison in this band, everything's too loud), or have a little duel song between Myung and Mangini. Maybe an ambient song (mellow instrumental like I said earlier) where it's just Jordan and Petrucci (or even Myung) improving slowly.
Stuff like that. Except they'll never do any of that (except for the mellow instrumental as a part of IT) because of the box they've closed themselves in. Shorter songs aren't risky, I have heard 0 strong opinions that shorter songs are bad, and if it were a risky move, people would be saying things like this is the death of Dream Theater, etc etc. Sure, many people don't like DT12 that much, but I assume that's more because of the songwriting than the length of the songs. Dream Theater haven't done too many new things recently. Putting a little string section in the middle of a song isn't that impressive or risky when the 6-minute overture to a song made 11 years before has a lot more to it than a melody from
Tchaikovsky's Piano Concerto 1 (that's a bit of an exaggeration, but you get my point).