Seriously, why the hell isn't there a second season yet?
People would love it and it would sell like hotcakes.

Because Hideaki Anno is a troll. He created Gainax to troll the otaku and he has been doing it with almost every series since Gunbuster. With the ending of PS&G, and four years passing with no second season, no manga, no nothing... he's trolled the viewers especially hard.

This should be no surprise. It's been over 15 years and people are STILL talking about how hard he trolled them with Neon Genesis Evangelion.

Gainax no longer exists. The studio that calls itself that is a mere shell of its former self with barely any of the original staff left.

Also, PS&G sold like garbage in Japan. Only foreigners liked it and we refuse to pay more than $5 per episode of anime, at best, so appealing only to us is a recipe for financial ruin.