My grandparents (when they were younger) and great-grandparents had very little spare change between them. But they always wore a suit and long dress to Mass each Sunday. Those times are no longer here. I can't imagine (fiscal) times being worse now than way back then, so it would seem it is a matter of choice. That, and society in general has eschewed formal wear.
Darn anon posting... that was me above.
Also, I wanted to add that I have about five pairs of suits, all pushing 20 years old. None of them fit me anymore because, well.... should probably spend less time online and more time in meatspace. Regardless, I do attempt to wear dress pants, dress shirt/tie and, depending upon the season, either a sport jacket, knitted sweater (or both), when attending Mass on Sundays. If I attend during the week, it's usually what I'm wearing for work, which is business casual.
I really should try to wear suits more often, but I never really liked wearing them. That being said, I can attest to the fact that people treat you quite differently when wearing suit as opposed to just about anything else.