In today’s Taanit daf, one is allowed to be immodest and behave like a Talmid chacham in matters where he has a loss – such as not working around 9 Av. So, someone who behaves like a Talmid Chacham (dresses up) in matters where it brings positive attention to him, or do it as part of culture – should not get your preference in shidduch over a guy who is not showing off.
This is not to deny reasons Avira and others bring why it helps community to stay strong by dressing certain way. Just to say, that someone who is erleche and yashar without dressing up is not to be looked down upon.