Today, when people don’t wear hats but do wear ties, it is probably more of an inyan to wear a tie than a hat by davening. Look at the pictures of the world leaders. That is how today’s royalty dresses- jackets and ties, no hats. That said, when the whole Jewish world wears hats, one should probably wear one.
As for hats/ jackets by bentching, I believe the Be’er heitev says ituf is only noheig in Eretz Yisroel due to kavod hashechina.