Unruly comes from reuly or easy to govern or reule to rule. I guess it is an English adaptation of the French word.
Unkempt comes from kempt to comb.
Disgruntled comes from gruntled to complain.
and non-plussed comes from plused, plusing, pluses, plussed, plussing or plusses which means to think, say or do.
So yes, some can be ruly, kempt, gruntled and plused. So what's your point? Guess I'm gruntled!