I guess that depends on what you consider quality. I think a significant portion of the changes can be attributed to the age of gamers changing and the people targeted slowly widening. For example, a common complaint that I see is how much more difficult all games used to be and how a more 'accelerated' experience is common now. To be fair, 'easy' is simpler to make but I also think the aging gaming population is partially to blame as well; some of us simply don't have as much time anymore and we're buying games that let us take things at our own pace with more progress/success rather than agonizing over that nearly-impossible last level for hours.
