Strange, the problem you experience actually is generated by Epic/Unreal themselves, it is they that encourage creators of assets to use larger/higher resolution textures.
I am old school, where if you apply a texture onto a door knob it has better be less than a 512x512 and a more detailed object/mesh to have better quality, but still optimised for the purpose.
Nanites is Unreals way of saying, Use Multi-Million Tri meshes and 8K streaming textures of your true realism mesh models, even if it is a door knob.
Posting texture resolution lists, does nothing for the Artist, as they may have a wide range of different door knobs in the scene at 128x128, because that is all that is needed. I’d love to offer a 512x512 for my door knob, in PNG 8 or PNG 24 formats, but Unreal doesn’t like them… That is after all the job of Mipmap generators.
When choosing my Textures and Resolutions for a pack, I strike a balance. Is the pack likely to be used as a foreground mesh that is going to be closely inspected, or a collection of distant forests.
In some other Engines, including Unreal I would provide bespoke shaders that were free to distribute, that gave additional features, like Edges, Transmission, Translucency etc, adding to the quality of the final render, as an Option. I supplied all the relevant map Textures, for the use to drag and drop in, should that extra quality be required, freeing up rendering calls, using combined maps to reduce the pack size. However, my first submission was rejected outright, quoting that I was ‘selling’ a free product under a CC licence. Despite the many confirmations provided by the creator that this was allowed under their license agreement, and the fact that shaders are Editor bound, unlike Textures and Meshes, Epic still rejected it. The very same Shaders were available for free on Epics own Marketplace. So now that flexibility of giving the quality required without bloatware, has been denied. So most creators of asset packs, err on the side that all of their goods will be scrutinised in close quarters. It is only the developers of compiled finished products that can fill their submissions with freebies.
That gives you some background on the why’s.
Oh btw, if your purchase any of our packs and want lower resolution/sized versions of the texture maps, drop us an email with confirmation of your purchase and the required reduced resolutions needed, and we are more than happy to do that work for you, free of charge.