Well… I’m 46 and it’s pretty obvious to me that we’ve been constantly moving towards more democratic societies during my lifetime.
When I was a kid, some western European countries (Portugal, Spain, Greece) were still dictatorships. Those became democracies.
Same thing happened in some Asian countries (Taiwan, South Korea).
About every single South American country was a dictatorship, and those all collapsed in turn, and there is currently none left.
Then there was the collapse of the iron curtain and all “east european” countries as well as several states of the former Soviet Union became free.
Just right now we have the Arab spring, despite its unpredicatble future.
Even sub-saharan African countries, despite their awful reputation, have become much freer (is that a word??) on the overall. Not even mentioning South Africa.
And I could find some other individual examples of countries moving from dictatorship to democracy (The Philippines), from dictatorship to a somewhat better state of affairs (Haiti), from vaguely to really democratic (Mexico).
And as mentioned by the OP, even China isn’t nearly as repressive as it was when I was a child/teen. I would even add that western democracies seem to be less willing to support opressive regimes (think of the USA propping up dictatorships in Latin America, or France doing the same, or worst, in her former African colonies).
So, until now, yes, there has been a considerable improvement. Democracies essentially didn’t exist outside of (most of) western Europe and North America when I was born in the mid-60s (Which doesn’t seem that long ago to me) Of course, it’s no guarantee for the future, but the more democratic countries there are the less acceptable dictatorships become.