The 1990 version also did a great job of fleshing out Tina McGee and establishing her relationship with Barry in the pilot. This new show didn't give us that when it came to the STAR Labs trio or even with Iris.
Well, it had more characters to work with, and more backstory to build up. We live in an age of more decompressed storytelling. Instead of telling a single story concentrated in a single episode, TV series today develop multiple stories in parallel over multiple episodes. We may get just as much development for the new characters, just paced differently.
I wonder what the red skies thing is about.
Ooh, I know this. Here ya go:
http://tvtropes.org/pmwiki/pmwiki.php/Main/RedSkiesCrossover