This video might help for a visual comparison as to what the 4k textures bring to the table (aka, not much). The biggest visual difference appears to be some tweaks to the lighting. If you’re looking just for a visual upgrade, not worth it.
That said, there is a FATE edition that at the current 60% off for previous owners, will include a new expansion in 2021. If you’re interested in that, it may be worthwhile.