Agreed, it’s going to be a while before everyone can take advantage of gigabit speeds. My streaming content both audio and video took a substantial leap when I upgraded to Gigabit speed (thanks to Infinity). Another key factor, wired ethernet to my Apple TV, brought much needed stability to my streaming. Also, I kept up with the tech upgrades every 2-3 years to take advantage of latest updates and features.
While I have not compared the two features you mentioned, I did compare Disney’s Jungle Book and had hard time distinguishing between the 4K Blu Ray and Stream on my Sony 4K OLED and Dolby Atmos setup. In any case, I get your point; not everything you own on disc may not look as good with streaming content.