Amongst leisure travellers maybe. Commuters used to crushes in the tube don't see 3+2 seating as an issue. In my experience football fans, another group used to crowds, also fill up 3+2 seating.
Think it very much depends on individual circumstances.
If you’re one of the hundred or so people who no longer gets a seat when your train changes from 8/317 to 8/379 then you probably prefer 3+2, especially if the journey is long enough that you don’t want to stand.
Everyone else probably prefers 2+2, though 3+2 can be more spacious on medium-loaded trains as it means less chance of having to sit directly next to, or opposite, someone.
So it’s a lot more nuanced than just “people don’t like 3+2”.
Certainly in GN days on 317s and 321s the middle seats were well used. Sure they were the last to fill, and *some* people chose to stand in preference, but the idea that they went unused is something of a myth.
The 365 seemed to provide a decent compromise - excellent 2+2 seating complete with good amounts of usable standing space, without the seating capacity suffering as badly as 387s or 379s. And worth remembering that the standing accommodation on the Electrostars isn’t great either, in particular the narrow aisles.