[hashmash]

The default limit is usually 25% of total physical memory. Should the default limit be the maximum? I think it's fine to have the default limit where it's at, to force me to think about what the actual requirements are. When you mean "tuning", do you also mean random GC tweaks? Those are generally best avoided these days, in my opinion. The auto tuning works well enough, and manual settings tend to cause more harm than good in the long run.

[hyperman1]

The problem is: when devs have learned about a necessary tuning knob, it's almost impossible to get them to stop touching it.

So recent JDKs have a sane default. Finally. Now we have a zillion app from the time defaults were not sane, each having a few -Xm parameters in their config. If they work well enough, nobody takes the effort to remove them. If they don't work, just type a higher number and test.

Manual JVM memory tuning will stay with us forever.