Greek Helmets. with or without crests.... ??

[Gaius Colletti]

We don't have any evidence that they were a status symbol or a rank symbol.
There is some evidence that specific groups had specific colours in their crests, but still, there is no evidence that crest colour was commonly used for identification of larger groups. After all, vases show phalanxes where the hoplites have different crest colour each.

I do recall reading somewhere that the helmets along with the crests were inspired to strike fear and terror into their enemies