Everything seems to be casual nowadays. Every other person wants to dress casually for work.
First impression matters. I am sure you have heard, you only have one chance at making a good first impression.
Dress for your role. You work attire should fulfill the worldview of the people dealing with you for the first time.
Yes, your skills should speak for themselves but before your skills can, you attire is doing a lot of the talking.
What are you wearing today?