I mean, I'm all for giving new creators a chance. It just feels like the proper way to handle a franchise would be giving the flagship book to a creator who proved himself on a lower-tier book while allowing the lower-tier books to be populated with new creators. Look at Batman. Snyder proved himself on Detective Comics and then was given Batman; Detective Comics was then given to John Layman, who has been given an opportunity to prove himself on a Big Two book after producing excellent work outside of the Big Two.
Cue The Bass in....
Venditti has been writing excellent indie books for a while and had a higher profile mainstream sci-fi book launch a little over a year ago and has produced a couple issues for DC that they've been keen on. Fialkov produced one of the critical darlings of the nu52. How are they in any way "less worthy" than Layman on Detective?
Also, why do people assume that Tomasi would want to write the main book? He's been doing GL stuff almost as long as Johns. Seems more than reasonable to me that he's equally done and would rather work elsewhere for DC or on stuff outside the company than plug away at GL for a few more years.