I see your point but I also disagree to some extent. You mention having sex with Lois without her knowing who he
really is as a problem. In the post crisis comics version Clark is the real person and Superman is the disguise. However in SR and the traditional Superman mythology, Superman
is the real person and Clark is a disguise. It isn't like she was having sex with a fake person. Also about sticking around to see if someone gets pregnant, that really points to the more fundamental nature of unexpected pregnancies.
They're unexpected! We don't know the details of their sexual encounter (and imo we don't need to know; there is such a thing as too much information!). Did they use a condom? Superman may have incorrectly assumed (as many people do) that it is a 100% effective means of preventing pregnancy. Superman also may have incorrectly assumed that since he is an alien, he wouldn't be able to have a child with Lois. Superman making a mistake of this nature isn't enough for me to turn my back on him. The bottom line is, I have full confidence if he would have known Lois was pregnant he wouldn't have left. That makes a huge difference to me. Also you mention Superman not telling loved ones as a problem. But let me ask you, how many loved ones does Superman have? Lois? According to Superman 2, whatever relationship they had was over. I don't feel compelled to tell ex-girlfriends of my future plans (although Superman indicates regretting not telling her). That leaves Johnathan and Martha Kent. Johnathan is dead and Martha?
He told her he was leaving. The one loved one he really had knew he was going.
What do you think? I'm not really trying to convince you, just give you a different perspective to consider. The reason I care about Superman in SR is because I see in him, someone who cares about others to the point that he is prepared to give his life for them. I've never seen a major super hero get injured so badly that he ended up in the hospital (in a movie). To me it made this film
and this character very compelling.