Yes, I agree with you absolutely, although the fact that the UI used to slam shut in our faces didn't make the "time-out" any more acceptable.The banker has always timed out on me after a period of time.
This has now become a big issue since it no longer closes the inventory window. As a result you can now accidentally use motifs / recipes etc when trying to withdraw them to sell, trade, etc.
This occurs with ALL bankers including Tythis. The merchant does not time out, and I see no logical reason for the banker to ever time out.