TBH, It’s more likely because the warhammer franchise predates the optics boom. In a lot of ways, we haven’t seen a major innovation in firearms operation since the AR15 and the AR18 came out in the sixties. There’s a few really innovative pistols on the competition scene, but pistols aren’t ‘important weapons’ to militaries.
Really, few small arms are ‘important.’ You just need ‘something in that role’ for the occasions the tanks and APCs and mortars are too much. The AR-15 and the AR-18 have between then about all the innovations you need for pure firearms function. Barrel in-line with stock for recoil control, etc. The main thing the 18 brings is a piston to an armalite system.
And so far, no one has come up with an idea at all that is radically better for small arms then one of those, the AR-18 is copied all over the world. (Most successful failure in history. No one liked it, but everyone copied it.)
What really sets modern weapons apart from the 1970s versions are suppressors, optics, lights, and designators.
On that front, there’s been a massive explosion. You have your old cross hair telescopes, your red dots, your red dot with magnifier, your holosight with/without magnifier, you have your tritium glowing nigh tsight iron sights, your etched prism sights… You have dual system weapons with offset red dot or iron sights and a big telescope up top, and that’s without mentioning all the night vision/ thermal options. AND without mentioning maybe a hundred really exotic or experimental ideas.
I suspect if warhammer came out today it would have all of that stuff as default. But warhammer is a bit of an old future. If you watch a lot of films made in the 1980s and 1990s, the space ships have old fashioned deep box monitors everywhere.
Today they would be shown with flatscreens. You can’t even get a new ‘deep screen’ anymore. Doubt anyone makes anything but flatscreens now. Most of those films, if they were good, stand up to the change, but you -still- notice.
Should we get optics? Yes, we need optics. Write any excuse you want. They are retinal implants that interact with the gun. They are holograms on the gun we didn’t see before because it’s only visable to the user. The Adeptus Mechanicus decided we’re ready for this technology and told everyone how to make it. Whatever.
Give us optics.