The respondent that gave the most interesting and least straightforward answers is Marty Pasko, interestingly enough.
The one who came off the worst (and I'm sorry to say this because I think he's great) is Elliot Maggin, who spent a lot of time in his responses comparing Superman to Abe Lincoln and mythology in a way that makes him seem a little crackers.
By far the most interesting and complex point Pasko makes - and where he diverges from the other writers - is that instead of saying "Superman is the 'true' personality" as Maggin says, or "Clark Kent is the real personality" as Len Wein says, Martin Pasko says that NEITHER is the truer personality. Or to put it another way, Superman was aware of his Kryptonian heritage so early on that "Kal-El/Superman" is a construct...but "Clark Kent" is likewise a construct as well, giving Superman a real degree of alienation, in the sense that he is two people that are to some extent artificial.
It's a shame Pasko wasn't allowed to write his secret identity exploring stories. On another occasion, Pasko said that if there was one piece of the Super-Mythos he would drop, it would be the Memory Chair that Superman used to return his memories of growing up on Krypton. He thought it would be much more poignant and tragic if Superman didn't have clear memories of his home planet.
For what it's worth, the one with the answer to the question that I found most satisfactory was Cary Bates. Superman and Clark Kent are so intertwined you can't tell where one starts and another ends.
PASKO: Was he? I remember it more as frustration and ambivalence than hurt: On the one hand, he was gratified that the disguise was working, but frustrated that at the Planet he was forced to keep playing the shlub when he didn't want to. I'd also suggest that he was skeptical that she really loved him, as opposed to having a romantic fantasy. I mean, how can you truly love someone-in a mature, committed way-before you know them very well? And since they weren't close enough for her to be entrusted with the secret of his double identity, it's doubtful he could regard her professed "love" as much more than an adolescent crush.
Even though Clark is an artificial identity, I don't think it's an "act" in the sense of a deliberately fraudulent alias, such as one a con man might assume. Rather, it's a displacement of Kal-El's deepest emotions and vulnerabilities into a manufactured vessel. I put it that way to distinguish the process from dissociation as in multiple personality disorder, because in Kal-El's case it's conscious, vitally necessary, and not at all pathological.
We all know that actors who work internally will draw on sense memory and facets of their own psychological makeup to make their characters as real as possible. In this process, it's not uncommon for actors to so closely identify with their roles that they start imprinting their own personalities on their parts. As a result, the actors so closely identify with their characters that the actors start taking what happens to the characters "personally." Often, actors in long-running TV series will feel that they've come to understand their roles better than the writers, and that's what starts the "My character wouldn't say that" wars. From that phenomenon, I extrapolate that, if he were hurt at all, Kal-El, the actor playing Clark, was hurt by Lois's rejection of Clark the character because that's the way the character Clark would react.
This is the most interesting response to why Clark Kent was hurt about Lois preferring Superman.
It's been my experience (though not universal) that writers that are the best at getting into the heads of characters - and can provide the most satisfactory answers about their inner lives - are people that understand psychology at more than just a shallow level. Steve Englehart, one of the greatest writers in terms of characterization, has a Masters Degree in Psych.
It is and has always been very clear to me that the character we are dealing with is Superman, not somebody named Clark who pretends to be Superman, and not Kal-El with some sort of alien consciousness who puts on Superman like a suit of clothes or a toga or something.
I'd be curious to know what Elliot Maggin thinks of Superman as he was written by Steve Englehart in his JLA run - where Superman was much more explicitly an extraterrestrial, marveling at Earth's expressions.
There was this big editorial meeting at some point where the publisher and all the editors at DC decided that from now on, the secret identity of a major character would be homosexual. Really. It was kind of silly.
Am I the only one dying to know who this was?
These characters have lives and dynamics of their own. The storytellers who are the most successful at creating time-worthy stories are those who best steep themselves in the characters' histories and traditions, and then simply tell stories, letting the characters take their own natures into their own hands.
Quoted for truth!
It's really tragic that AVENGERS hasn't really "felt like" Avengers...really, since Busiek left.
That's just one example, of course. Green Arrow hasn't been himself for decades.