But I think you missed something.
This particular thread is about Barry Allen
or the Flash, not Bruce Wayne.

Concerning the following;
>For the power of SHAZAM to be actually useful, only a
>person of pure heart and innocence can wield it. Flash, no
>matter how flag-waving he gets, is an adult. Billy was
>chosen because he was just a kid with a gold heart. He has
>plenty of innocence left to him.

Black Adam was not a child when he received the power of
Shazam. True he wasn't pure and innocent, but that wasn't
what made Black Adam evil. Adam was evil to start with.
and NO WHERE can I find that Barry Allen had any selfish
ambition that guided him.

Now on a third point, someone emailed me back when my
my message board was down for almost a year, they had an
interesting take on Bruce Wayne. (can't find the email
at the moment, I hope the sender is reading this and will
post their idea about Bruce Wayne becoming the Flash.