You're right, but probably the answer to your question would take away in the limitations of DAZ as a 3D program.
DAZ is an old and weak program, which is practically not developed. It still lacks such elementary functions as snapping and practically no simulation. DAZ works at the level of 2014-2015.
Most of the assets that are sold in DAZ are assets of professional visualizers who sell their models that they used in their architectural visualization projects. These are good models, with good topology, but probably due to some technical limitation they can't sell models with high quality textures.
I don't know what polycount is in DAZ, but I assume it's pretty low, up to a million polygons. For comparison in Zbrush you can create a model with hundreds of millions of polygons.
What can be done? Probably DPC needs to hire its own 3d modeler who will make models based on its references and texture, preparing for import into DAZ.
But DPC has already shown that graphics is not at the top of his own list of priorities.
Sorry, but I beg to differ... First, Daz is not that old compared to other programs, and, second, being old doesn't make something bad -- Photoshop is quite old and it's still the industry standard for photo editing, just to give an example. Daz is quite good for what it was created which is posing -- it started as a Poser competitor. And it's also good for character creation, because, even if software like ZBrush is, in theory, superior, it's a digital sculpting tool (besides being also a texturizer) that needs real talent to make something good (as in real-life sculpting) while, I bet, most of us can create better characters using dials than trying to sculpt something. It's like those softwares for drawing with tablets (those with a pen a not the tablets that look like a big cell phone) that the program can be amazing but, if you don't know how to draw you'll suck big time and it'll be useless for you. Moreover, the fact that a software isn't complete, doesn't mean it sucks; it's like saying ZBrush or Photoshop suck on animation -- indeed! They were not made for that!
About the polygons, in fact, I have to confirm the exact numbers, but they've been lowering because you have subdivision, that has been around for a while but, with better graphic boards, you can properly use it. It takes a toll on your graphic board, but, having the right equipment, you can subdivide a lot in Daz. On the other hand, people create figures in ZBrush with loads of polygons but, unless they're from Hollywood rendering on supercomputers, they export a lower mesh and bake the details on normal and displacemente maps, because polygons also take a toll on your graphic board memory. Also, unless you're doing closeups, most of the time, the polygons of a genesis figure with a subdivision of 1 or 2 will be good enough and no one will notice a difference (there are even plugins to adjust the subdivision of every object according to the distance from the camera).
About the textures, right now, 4k is standard (the 8k they were advertising is just for the micro details normals), which, by the way, is relative -- what matters is the size of the texture proportional to the object rendered, thus, even if all materials are 4k, the face has a better resolution than the torso, because the face is smaller. But that's not the main topic here, but the fact there's no technical limitation in Daz, and, if you don't like the 4k textures, you can create your own the size you want. Again, most of the time it won't matter unless you're doing closeups, but you can do it. But, also, the size of the textures takes a toll on your graphic board memory... So everything has to be managed... And even DPC with his top-notch computers probably considers the size of his scenes because, as you add characters, clothes, environments, props, hair, and everything else (in case I'm forgetting something) it increases rendering time...
But, yeah... There's one thing that Daz sucks which is animations... It's not that it is that bad, but, since it uses the posing logic and not a physical simulation one, you have to pose everything while in other physics-based software, it will take care of some of those details for you (mostly, the part of collision and the effects of gravity). Again, it's something you can do -- and I think DPC is doing it fairly well (he's one of my top 3 animators along with the guy from Betrayed, and the guy from the Beauty and the Thug -- those using Daz; the guy from Mist is very good, but he uses Blender) --, but it takes a lot of work because it's like doing those stop-motion animations with real puppets wherein you have to pose, film a frame, pose, filme a frame, and so on, with the difference you pose everything and, then, render, but the grind of posing is almost the same.
So, my conclusion, is DPC doesn't need to change anything in his framework, at least, for this game. The characters are already done and, even if could there be some improvement, it would be very weird to see a different Sage, Maya, Jill, and so on. His characters may not be entirely original but they have personality; and even if he uses many out-of-the-box models, at least, he's smart enough to choose ones that were not used before (or, at least, not overused). So, when we see P3D Imogen in another game, we think "Oh! Look! It's Jill!"; when we see Kayleyss's Aurore, we think "Oh! It's Quinn"; when we see iST Hyuna, we think "Oh! It's Rionna!"