Its up to Netflix and Youview not BT to get in to talks about a Netflix app update.
The Netflix app on my Youview boxes dont look that much differant to the Netflix app on both my Samsung full HD smart TVs that are now a good few years old. Even on my sisters 3gen Apple TV box at her house the Netflix app seems much the same but seems to have a better sound output. I dont watch the programe you take about but for me the Netflix app seems ok how it is the now and most programmes that I watch on Netflix seem to be in full HD 1080 as well 90% of the movies that are on Netflix. Where is I sometimes find that some movies as well as some TV shows on the Amazon Prime Video app are only in HD upscale or just 720 HD.