I would assert that "quality of life" as a function of unknown variables across the entire human race does not change significantly with time, viewed at any large (decades or centuries) scale. The average value of that function will be more or less the same no matter what time period you take your sample from.
In other words, average quality of life now is more or less the same as it was when humans lived in caves, or during any other period up until now. I think "quality of life" has a lot to do with the ratio of people who would claim to be "happy" vs. the people who aren't happy, but that is open to debate. I don't claim to have an authoritative definition of quality of life. I don't even claim to have decided on one for myself.
I think the human race calibrates itself to the situation in which it is forced to exist such that the same global levels of happiness and unhappiness can be observed for any time period. Variations will exist in the short term (maybe wars, depressions, etc.) but even they will be canceled out in the long term.
Part of what I am saying is that technology has no discernible effect on the human aspect of life. I will come back to this tomorrow when I am sober.