Sorry if I missed the study, but what makes this all because of preorders? I've been playing buggy games for decades, plenty of which I didn't preorder, many of which weren't even expected to be huge hits, why is everyone so sure that preorders are why developers aren't fixing games? I'm not saying they definitely have nothing to do with it, but as someone who preorders a game about once every year or two, I'm genuinely curious what evidence there is that my actions are damaging the games. And for anyone thinking I'm a dumbass for preordering games, I like to get collectors editions of sequels to games I already enjoy because I like having cool things to put on display to represent those games. I genuinely like that extra stuff, lots of people do, I'm not saying you should but don't give people shit because they like different things.
To be honest, I think it has more to do with priorities changing at major game companies. It seems to me like the industry started off as gamers making games they enjoyed for other gamers, and making a bit of money off it. As the industry has grown and become more profitable, many of the people making the games aren't as passionate about the games themselves and are more concerned with making money. This is fairly obvious with larger companies such as Activision, franchises like CoD have a new release every year instead of even attempting to make a game one would enjoy for longer. And we've all seen the Destiny fiasco, a game I enjoy but am getting fed up with at the same time. It seems to me they're just choosing quantity over quality. That's really just me guessing, but without any evidence one way or another, I think anyone's guess is just as good.