There are a number of packets that depend on this, so you can't just remove it. Although you can recompile it to disable data collection, it's not something everyone just does.
* Opt-in.
* Has several different levels of sharing and pretty clear about what is being shared.
* Even at the most relaxed level, it's fully anonymized.
The only criticism I've heard about it a long time ago was that even if you turn it off, it still will collect the data, locally on your machine. Which was a technical matter at the time and may have already changed.
KDE people are among the most privacy respecting bunch. Grandparent is spreading FUD (or has been misinformed as result of FUD). In a world that people are comfortable with Facebook and Google I find it funny that people would have privacy complaints about KDE.
Disclaimer: Used to be a minor kde contributor.