There are two main reasons why in some institutions, members are required to adopt a specific dress code: 1. Professionalism - you do not come to that institution as you go to the beach or to a barbecue. Clean, ironed and elegant clothes broadcast dedication to the job 2. Respect and norms of behaviour towards your colleagues and "customers". What is more normal for the Knesset members than showing the example, without arrogance, to the people, and stop considering the Knesset as a factory Histadrut meeting of the 50's?
from the article: The non-Israeli Knesset