Is Spielberg One of Our Greatest Directors, Or One of Our Most Overrated?

This question came to me recently after rewatching the entire Indiana Jones series over the course of a few days while sick. While the first film was incredibly entertaining and iconic to me as a child, the narrative borders on the absurd and the quality seems to diminish with each subsequent effort, though the third was better than the second and fourth installations in the series. I have often had discussions with friends about Spielberg and my argument that he has contributed in a nonpareil way to the destruction of Hollywood, even as I loved many of his films growing up. How, might you ask? Well, in four ways in my estimation:

1. The creation of the summer "blockbuster" with the release of Jaws in 1975. I think it is a good film, arguably broaching the theme of the fear of downward mobility so many horror films indirectly hint at, but it is credited as one of the first blockbusters of the modern era and certainly can be highlighted as the source of the horrible collection of flamboyantly average "blockbuster" films that each summer now proffers as we await another Oscar season barrage of quality.
2. In the same vein, it is arguably Spielberg who popularized the sequel, the prequel and the endless succession of films in a self-enclosed mini genre of one that now dominates the Hollywood landscape. Fans are invariably willing to settle for mediocrity in these follow-ups, no matter what the critics say, and it can thus be argued that they have helped lower standards of quality in the industry as a whole. It should not be ignored that they have also made Spielberg the second richest man in Hollywood (behind friend George Lucas) and one of the richest men in America to boot.
3. His infamous product placement in ET: The Extra Terrestrial (1983), while not the first instance of this practice, made it a normal and lucrative side-business within the industry and helped usher in the notion that no place was sacrosanct for advertising. 
4. The first three arguments are certainly not unique, but I think the fourth one might be, and could probably be critiqued heavily. But here it goes ... I believe Spielberg exoticizes violence in a way that was rare at the time he started to do it: first in the Jaws films and then later in the Indiana Jones oevre. Starting in the 70s, there were a number of Hollywood films that looked at violence in a more realistic way, while actually seeking to explore its complexity, and the birth of the modern horror film could also be charged with this tag. But while Scorcese can certainly face the same charge (and I think rightfully so), he does so in gritty naturalistic films that offer a more nuanced view of violence and its ramifications (though less so in Goodfellows than Mean Streets, Raging Bull and even Casino). With Spielberg, the violence exists in the fantasy world he conjures, thus eliminating its instantiation in the real and allowing it to exist as something we can take pure pleasure in. Indiana Jones is killing Nazis that are even more caricatures than those of the 40s and 50s, and we can thus watch their faces melt off or watch them thrown under a tire without the requisite notion of horror. Dinosaurs eating or ripping apart humans in a fantasy island of the future certainly doesn't necessarily relate to the violence in our streets. And even Jaws, as realistic as the first film might have felt at the time, became so absurdist by the third, that we could laugh as the savagery unfolds in front of us. 

Some may point out later work like Schindler's List, Private Ryan or Band of Brothers as doing the opposite, but even here I'm not sure I agree. Where does the gritty realism of extraordinary war scenes move from the artistic phase of naturalism to the rather obvious, but cloaked pleasure in seeing violence and death on film? How do we come to terms with the end of Private Ryan, and really the entire story, which really becomes almost cartoonish in its simplicity and homily to the clear line demarcating good and evil. And this has always been the problem with  Spielberg's work to me. There is very little nuance. There is pure good and pure evil, one right choice and one wrong. Actions which are acceptable and actions that must be punished. Unfortunately, it is only in the world of cinema and politics, where we can even pretend at such a Manichean worldview. And yet Spielberg has subsisted here for most of his career. 

Don't get me wrong. As I child I loved many of his films from Jaws to ET to Close Encounters and Back to the Future, but his love of the world of fantasy and make-believe, his Capraesque tendency toward the tidy happy ending, his rather obvious and persistent racism (go back and watch the old films paying attention to his portrayal of Blacks and native people), his tendency to make films that will make money over films that have artistic value (and quality in some cases) and his position as the one who may have ushered Hollywood from its most creative, artistic period (in the late 60s and 70s) into the blockbuster world of today, may overshadow that success just as we should continue to ask serious critical questions about Disney and it's ideological machine. In a few days, I will ask another related question .... who is more overrated -- Spielberg or Ron Howard (though the answer to that is probably obvious). I'll finish by saying that Spielberg does have an uncanny ability to turn films into magical endeavors that touch our hearts and become iconic pieces of our cultural history and his technical abilities are extraordinary, but I have always been drawn to the question of quality versus success, and wonder if his endearing drive for the latter didn't undermine his adherence and dedication to the former.