Yeah we've gotten away from the times where it would be taboo to have a lead character past 30 and right, it doesn't change Superman anyway.
I imagine the earliest Superman wasn't much older than his creators, but that was back when moving out from home and receding hairlines were both very common for those in their early 20s. These days you have tons of working professionals who didn't start on their career path before 25.
Continuity wise, we've also advanced... to the point where all you have to know is NOT contained in the current run. But people have so many resources and often like researching to the point where you can partially excuse creators for skipping the leg work. CoIE and the following timeline would be completely different if executed now.