The main issue with the factory T1x stock is it needs a lot of accessories right out of the gate: butt pad (to increase LOP), vertical grip, cheek riser.
Meaning it's a lot less value than the CZ457 options, and not as suited to base class for NRL.
The UPR fixes all of these but is pretty expensive so most people would rather just get a chassis on the base rifle.
If they offered the adjustable cheek piece stock (from the super varmint/tactical) and a heavier weight barrel, they price shouldn't change to dramatically but it would be considerably more competitive with the CZ 457 options.
If the teamed up with MDT, KRG, GRS etc and did a factory chassis then that'd be even better.
But as it stands you either have a rifle that isn't the best choice for base class, and requires a lot of mods for open class (chassis and barrel) that it's easier for most people to go CZ 457.
I bought my T1x very early and while it's been great, I would've bought a 457 instead if that was available at the time.