Here's the thing for me: when they moved from 2e to 3e, they gave us a game that felt fundamentally different and gave us a new way to play. The same happened with the 3.5 to 4e transition, and again when 5e came out. I like having a variety of ways to play, and even if I eventually decide I liked an older version more, the novelty of a new experience is nice and helps me think about how I want to run or play whatever else I decide on. And it's not like your old books go away. Like I liked 5e at first, appreciated some of what it was doing, started getting tired of some things, then went back to running 4e, as I felt it fit what I wanted out of a game better, but still appreciated my time running 5e. When I look at the D&D One playtest materials, my main thought is "if I wanted to play something that felt like 5e, why wouldn't I just play the 5e I already have?" It kind of feels like when you buy a vacuum on Amazon, then it keeps recommending you more vacuums. I already have one of these, I don't need another.