No lawyer would appear before a Judge in Court to represent his client without a jacket.
Is Hashem less than a goyishe judge?
A lawyer is an officer of the court. A respondent, however, is not and you may find cases where respondents DO appear before judges without jackets.
But let’s carry it a bit further. No lawyer would appear without a tie either. Yet I see no one saying that one must wear a tie to davening.
Is Hashem less than a goyishe judge?
The Wolf