I think the genetic engineering reveal actually ties up a couple of strings of Bashir's character. He missed a simple question on his final exam and lost out on being valedictorian. He could have been a tennis pro but never made it. To me, it makes those earlier episodes even more interesting after learning his secret.
Well, I'm going from memory here, but... doesn't the genetic engineering change the motivations for all of that? He's really smarter than everybody, has better hand/eye coordination, etc., but is trying to "blend in"?
DS9 is full of things that weren't planned out in advance, but end up working pretty well when you look at them in hindsight. One of Trakor's prophecies, for example, way back in "Destiny," was about the Emissary facing a fiery trial. Fire caves, anyone?
Bashir's genetic alterations aren't that different. Sure, they put his previous actions in a different light. So what? As you get to know someone in real life, their previous actions may make more sense as you learn more about them.
And Bashir's not the only one to receive this treatment. Eddington's behavior in "For The Cause" puts his conversation with Sisko in "The Adversary" (the one about command versus security) in a different light, should you choose to interpret it that way.
As for Bashir being salutatorian, deciding not to pursue tennis, hell, even his decision to leave Earth and that cushy surgery job in Paris, I tend to think that those weren't so much conscious attempts to blend in as they were the unconscious results of a psychology that's been forced to lie for an entire lifetime. When you must keep something a total secret, you don't keep it in the forefront of your thoughts. Bashir didn't spend 25 years of his life saying, "I can't do that because it'll make my genetic enhancements obvious," he spent 25 years of his life saying, "I can't do that," out of habit.
In some ways, his genetic status helps explain some of the early flaws in Bashir's character. For one thing, as young as he is, he is still much less mature than you would expect. Stuff like that sometimes (not always, of course, but sometimes) is the result of childhood/adolescent trauma that knocks your development off-kilter. Bashir's got a few episodes in his past that could qualify: undergoing a major medical procedure that he didn't understand at age 6, finding out ten years later that his parents had made his entire life a lie... you could even argue that his early childhood deficits were traumatic, though I wouldn't personally make that argument, since it doesn't seem (from the episode) that Bashir felt particularly traumatized by this
phase of his life.
Also, his boyish enthusiasm could, in fact, have been a cultivated "safety net"; if he slipped up and did something truly extraordinary, it could be chalked up to all that enthusiasm. It wouldn't surprise me if something like that had happened somewhere in Bashir's past, and he discovered by accident that he could extricate himself from the situation by being so darn enthusiastic.
Bashir's lack of relationship with his family is hinted at in "Homefront," when he tells Odo that there's no one on Earth for him.
Bashir's penchant for spy games could be a convoluted way for him to deal, psychologically, with having to hold such a big secret (and maybe a few other related ones).
Even Bashir's "Not quite. Close." story to O'Brien in "Armageddon Game" has a bit of a Garak quality to it, as if the truth is indeed in there, but is being... simplified, for our benefit. I wouldn't be surprised if Bashir turned down the cushy surgery position because he knew it would catapult him too high too quickly, and give reason for scrutiny.
Indeed, Bashir has had to live almost his entire life with a little voice in the back of his mind saying, "Don't be perfect. Don't be perfect." His early social flubs with Kira and O'Brien (and Dax, too) spring to mind.
Honestly, without some sort of revelation, I think Bashir would've ended up being the least developed and least interesting character in DS9. "Doctor Bashir, I Presume?" suddenly makes a whole lot of would-be missed opportunities in early episodes more interesting.
I'm not sure the Section 31 storyline could have happened without "DB,IP?"; 31 needed a reason to be interested in him beyond his love of spy games. Making him enhanced tosses in the whole question of playing god (which Bashir does as a doctor already, see "Life Support"), and weaves in some discussion of elitism/eugenics, which 31 try to use to manipulate him.
Also, I'm not sure I really see that Data/Spock parallel; DS9 had Odo (and to a lesser extent, Quark, Worf and even Garak) to do that. If anything, Bashir became a humanized version of Data/Spock, removing the observer status. But even that parallel is superficial at best, imo.