my point was that the timeslot is obviously a factor if they put the big shows that need a lot of viewers to be successful out front. i've already said i don't see how something like Fairy Tail is going to bring in a greater number of viewers; all it's going to do is maintain the status quo.
if you consider 1am to be the top of the block, sure. piling a bunch of the long-runners you suggest up until 2am is completely artificial; it's largely the same audience. all it does is coax the same people later into the night, where they're more and more likely to get tired and shut off the TV rather than give those shorter shows a chance. and what about the people who don't want to stay up that late but don't find the genre appealing? what about the people who would rather change the channel than sit around for 2 hours of similar programming before they get to something that interests them? the death of variety in those opening hours only limits the potential audience.
I think Fairy Tail would bring in some new audience, and even if it didn't if it could maintain the status quo and do Bleach numbers (again one of the top 4 highest rated shows Toonami has ever aired) then that'd be pretty fantastic.
And this variety you want, Toonami is an action cartoon block... even if it isn't long running shonen 90% of the shows are going to involve people fighting each other. Currently the only shows that don't do this are IGPX which is two teams racing and GitS which is Anime CSI. Even FLCL manages to fit a fight scene between two robots at the end of each episode.
And lets face facts, the Toonami block has done better ratings wise with a 2 hour top block of shonen then it ever did before that point. The Toonami you seem to want was a year and a half ago when the block was Bleach, Samurai 7, Eureka 7, GXP, etc in the top two hours and these shows clearly weren't doing it the way Naruto, OP, and Soul Eater do. The fact is the niche amount of people who might have wanted to watch the newer shows that air in my hypothetical block from 2-3 don't match the larger number of shonen fans who'd rather watch 2 hours of shonen crap and then go to bed. You have to appeal to the largest audience and the money and numbers clearly point to long running shonen being the key to success. In all of Toonami's years the only not long running show to be one of their big money makers was Gundam Wing a 50 episode mech anime.
Let's just say Toonami hadn't gotten Naruto/One Piece/Soul Eater and had SAO at 12:30. Sure at first it may have done really good Naruto esque numbers after Bleach, but by this point the numbers would have completely dropped off the deep end as people quit the show for being bad, SAO fans quit the show because they don't like part 2, and those who remain only stayed because they were going to watch the whole block regardless.
It'd be like arguing for Adult Swim to not show dozens of reruns of Family guy and instead do a wider variety of their shows, sure they could do that, but when syndicated Family guy makes them far more money then syndicated random crap what's the logic in changing? Making a whole bunch of new shows probably going to make you as much money as what you're audience clearly wants. Toonami's audience clearly wants and likes shonen and that's why they tune in every Saturday night. There isn't some mass amount of on the fence anime fans that can suddenly be converted by shows like Space Dandy or Titan or any other random anime.
Again I'll repeat, Bleach is one of the highest rated shows on average that Toonami has ever aired in it's history, if Fairy Tail maintains that status quo it'd also be one of the highest rated shows to air in Toonami's history. How many anime or western action cartoons could do better then Bleach at 12:00 or rerun Naruto at 12:30? Not very many, and those shows can go at 11:30 in the big premier slot.