No. I like being able to periodically check and see how healthy my respiration is going. If it drops below 90%, I might think twice about certain things / otherwise good to consider checking myself and watching for anything further that might require medical attention. I love my physical health and wellbeing so this is great.
If you want to know what I would say is a good example of a 'gimmick', look no further than the 2020 iPad Pro's LIDAR scanner. Source: have the 2020 iPad Pro. 6 months on after release, including iPadOS 14, and LIDAR still has absolutely nothing to show for it besides the IKEA app and some games that are locked behind Apple Arcade paywall. I'm gunna come out and say it, but really, in its current form, the LIDAR scanner is truly useless. It may as well not be there. It doesn't even have its own dedicated app or anything else to showcase it, unlike blood oxygen in the S6