I see what you're saying, and I partially agree, but Asthenia was put out before AVA existed, so if AVA had never come to be I doubt they would have continued to go down that road. But with Tom writing songs that way for six or seven years it bled into the new blink album. And sure they have the same singer/guitarist/songwriter but you didn't hear Alexisonfire putting out a bunch of songs that sounded like City & Colour did you?
My point with Asthenia is that it sounded like it could have been an Angels song, so Tom's writing was always going in that direction anyway.
And comparing C&C/Alexisonfire with Blink/Angels makes for an absolutely ridiculous argument, as Dallas covers completely different ground in City and Colour, whereas both of Tom's bands play genres not too dissimilar. Anybody in a hardcore punk band could write an acoustic song that sounds completely different from their usual stuff, but it's quite blatantly going to be a lot harder writing for two rock bands.