This is equivalent to something I called the "QWERTY paradox" more than a decade ago:
Back when the Smartphone market exploded, people disliked typing on a touchscreen and repeatedly stated that they want a device with a physical keyboard.
There was plenty of evidence, surveys, market studies, trend predictions, devices for these "Messaging-centric" use-cases were always part of this market-demand roster.
But whenever someone answered the call and built a Smartphone with QWERTY keyboard, the product failed commercially, simply because also to people claiming they want such a phone, at the point of sale they were less attractive than their slimmer, lighter, all-screen counterparts.
Every major vendor went through this cycle of learning that lesson, usually with an iteration like "it needs to be a premium high-spec device" --> (didn't sell) --> "ah, it should be mass-market" --> (also didn't sell).
You can find this journey for every vendor. Samsung, LG, HTC, Motorola, Sony.
The same lessons were already learnt for small-screen devices: There was a "Mini" series of Samsung Galaxy, LG G-series, HTC One, Sony Xperia. It didn't sell, the numbers showed that it didn't attract additional customers, at best it only fragmented the existing customer-base.
Source: I work in that industry for a long time now
People do ask the wrong questions.
Yes, I would buy the phone with the keyboard, but the keyboard is not the single most important feature. After the Desire Z there simply was nothing comparable. If it was 400 instead of 300 I would have said no, if it was from a brand I hate because they mess up the default Android install I might have said no. If it was 1:1 like some other phone except the battery being atrocious I might have said no.
The problem is that they are changing 10 variables at a time, including size, cost, software, camera, battery, whatever.