The overall trend is that justice and respect for human dignity has steadily, undeniably, increased over the last several hundred years. Therefore, generally speaking, I would say that yes, a modern 30-something has more "decency" than one of 50, 75 or 100 years ago.
To be totally clear, I don't fault my grandparents or other people that are products of these eras. They aren't necessarily bad people. And certainly, the measure of "common decency" would, of course, be different then.
I just can't wrap my head around longing for a time when society was more constrained/repressive/intolerant. Yes, there are things I think were better in the past, but they are the exception.
(side note: this is not to say I don't think political correctness can go too far, it certainly can. There are exceptions to everything).