I felt the Jackson kids were dressed a little sloppily for Kingdom Hall attendance. Obviously they'll be cut some slack because they're new and their dad just died, however, by Christmas they'll have been taken aside by a friendly, elderly elder (sorry for the tautology) and told that they need to smarten up. Oh, and cut the hair.
As for what we wear playing any sort of role in our worship....well, it only plays a role if what other people think of us matters when we worship God. Making it about us/how we look/what others think about how we look actually negates the whole point of worship. Think about it...
Plus isn't there a scripture about how Jesus doesn't judge on outward appearance?