Yes, ATV4 has issues. But it's also a big revision that gives the ATV functions it never had before, namely apps. I find myself willing to put up with the glitches and regressions for the new features -- for example, I found this nice tennis app that is perfect for getting in a little exercise. That wasn't possible with ATV3.
First, I am glad you found an app you enjoy. Second - it seems that you already put up with the ATV3 not being capable of doing what other devices already could do. The ATV3 was behind the times and the ATV4 kinda-sorta brings, with a bag of hurt/problems, what was missing for a long time. I don't find it to be a huge jump given that the technology/software/firmware capability was already out there and more so since Apple had this ability on other devices. Bottom line is that if people are enjoying the ATV4, this is a very good thing and if people are not enjoying it, then it isn't serving its purpose for those people. In my estimates, ATV4 should have been called ATV 3.1.