Personally I don't like companies tracking what I do constantly. If I had the possibility, I wouldn't allow my credit card issuer to profile me based on my purchases. I'm using "deGoogled" Android to limit Google's ability to monitor what I do on my phone, and I use both ad block and privacy badger in my web browser. I'm not saying what Fedora/Red Hat is considering is the same as what Google, Facebook, etc are doing, but in general, I'm against being tracked and monitored.

Now one might argue that software telemetry is much more benign, that they're only collecting data about their software and not about me. The thing is that I don't trust businesses to actually care about me, the end user, and I assume they're going to fuck me over the second it becomes the more profitable option for them. I could spend time and energy to read up on what data they collect from my computer, but that sounds kinda tedious and boring so it's not like I want to. And even if they completely anonymize the data now, I'm not confident that I would notice if they changed their ToS to allow them to collect more data and sell it to third parties at some point in the future. It's just so much more convenient for me if there is no telemetry to begin with.

But I can definitely see why company collecting data would prefer opt-out.