Our bedroom TV is a Samsung 4K, and I prefer using a Roku over the TV's streaming apps. I had a 4K Roku Premiere attached before replacing it with the Roku sound bar - - the TV's built in speakers sucked.
Using an inexpensive streaming box solves this issue. I have two Vizio 4K displays and never use their smart TV feature. One display has a Roku attached, the other has both an Apple TV 4K and Roku. Same with our Samsung 4K display, which has a Roku sound bar.