I would be very surprised if Keith Baker said that no aspect of Eberron was designed because he thought that he could improve upon parts of other settings (the Superman stays out of Gotham problem that's rampant on Toril, the religion problems that many other settings have, etc). There are many parts of Eberron that are obviously designed as "let's take a part of the assumed lore of D&D and aspects of other settings, and deconstruct and subvert them in better ways". Not that that's a bad thing. I think Keith Baker has proven that he's very good at doing that.
As
@Faolyn said, there are parts of the setting that changed aspects of other worlds for reasons that aren't just "the logical conclusion of how D&D is designed". That is a major part of the setting's design, but there is also a reason why the setting has no metaplot or high-level benevolent spellcasters that could do the adventures instead the PCs. There are parts of Eberron that were definitely designed as a "let's take that bad thing from a different setting, and either change it to make it better or ignore it completely".