You forgot Anton Yelchin (18)  
 
Y'know, perception goes a long way towards making or breaking buzz, especially when the likes of Hollywood Reporter 
say Warners was casting 19 and 20 years olds for JL.  True or not, the perception among those who were aware of the production was that it was being cast with a bunch of young nobodies, and that didn't sit well with anybody, apparently.
And this...
Is contradictory at best.  If the script was so good, why'd it end up on a "blacklist?"  (Never heard that, but whatever.)
When the film was first teased as being in development, the consensus seemed generally positive.  Big budget.  Known production team.  FX house.  Costumes.  The works.  Then things got shaky with conflicting information about the script, which had been touted as no less than awesome on a stick by people such as Greg I'm-so-confused Noveck, Senior Vice President of Creative Affairs @ DC Comics...
10/17/07
GREGORY NOVECK: The reason that Justice League is powering forward first [before MOS] is because the script came in and it was phenomenal.
VOICES FROM KRYPTON: It's really that good?
GREGORY NOVECK: It is, and that very rarely happens in Hollywood on a movie of this scale, and when it does you have no choice but to say, We'd better catch lightning in a bottle and go! All of a sudden, six months later, who knows what's going to happen? You want to hold on to those writers, you've got massive interest from directors, you land someone like George Miller, so you go...
http://www.voicesfromkrypton.com/2007/10/dcs-gregory-nov.html
Opinion changed fast, I guess.  Maybe somebody actually read it at some point, I dunno?  
 
I was all for a JL film.  I didn't have any issues with there being casting "confusion" with other established franchises (Superman, Batman, or even Smallville.)  I didn't have any issues with George Miller, the production team, rumored script elements or character choices.  The cast however, left a lot to be desired, and that's an understatement.  To this day, people still b**** about Gale, and lets not even mention Hammer or Cotrona.  And no, it's not just fanboys - unless the entire internet is populated by them.
Then again... maybe it is?  
 
*goes back to happy place*