I always hated dressing up. Spending a decent percentage of my adult life in the slightly to more than slightly overweight it almost always feels like I'm being strangled, especially the tie. My family also carries the double-chin gene so even the largest neck shirt with expanding top button cheater seems rough.
For a long time my fashion goal at any social event was to be the second worst dressed person there. I didn't want to stick out as the worst, but I figured if someone else was more casual than me, the church ladies would gossip and point at him/her.
That being said I always at least looked clean and presentable, not wearing "Grateful Dead" tee shirts to funerals, etc. And I do appreciate the well presented man or woman in a nice outfit, and yes, have even dressed up myself and been the BEST dressed at events. For me it's more the relationship - For a family funeral or wedding you dress up. For a good friend you dress up unless they never dressed up. For casual friends, non-close coworkers, neighbors, distant relatives, I just go with khakis and a polo/golf shirt.