People follow their biases (real or not) when they act. We recognize this to aid the learning/business process. If one shows up in a T shirt & jeans to the court, they will not be taken seriously by the judge (any dress codes aside). Showing up to give a shiur as such may have the attendees believing, however much incorrectly, that the material is not “on the level” or the one giving the shiur is not qualified (similar to the judge, or the boss who has the prospective employee show up in shorts).
WE may claim we are not biased, and for you it may even be true, but those who are listening are.
(This is all just to illustrate the point, not to argue one side or the other)
SJSinNYC:
Well put, but its not your standards, but the standards of those who are attending as well. If i wanted to give a shiur in KJ (just as an example), a suit, white shirt & tie would be still be underdressed.
Perhaps where cantoresq is it is normal for someone giving a shiur to wear clothing as such, so who are we to judge on that point?