Formality is bad. It is another layer of separation between you and the work. Way back when the original meaning of 'informal' simply meant your employer didn't care about non-work-related stuff like attire -- but its morphed into a culture of its own, destroyed perceptions towards those who really are results-oriented, and sent a lot of people down this path thinking formal is better. A lot of don't want suits at our workplace, but neither do we want ping-pong tables, or even beer (gasp!). We want to be left alone to do our work so we can go home on time and live a happy life.
I think we can thank business-management types, this obnoxious brogrammer culture, and all the not-really-a-computer-nerd-but-I-learned-to-code hacks for the culture we have now. Leave it to the muggles to ruin everything...
sigh