On Java 8+, you can use G1 GC which has very few knobs. On the other hand, CMS GC has a lot of knobs you can tune depending on your workload. JVM (Hotspot in this case) believes in flexibility over a one-size fits all. YMMV.
In other words, there are actually knobs that have you choose the GC, and then choose settings within the GC.
Tuning is a hassle, but when the alternative is rewriting my important code over and over until I hit the right tradeoff between fast and readable, I'll take it.