Squadron Hawk isn't supposed to be a Baneslayer/Titan replacement. More than anything, it's like replacing Wall of Omens (ROE) in white/blue control. Brian Kibler used Squadron Hawk (M11) (deck name "Caw-Go") in his white blue control deck as part of his deck's strategy; this isn't your grandmother's white/blue control deck. In addition to providing one-card-for-three-type card advantage (which is insane), Squadron Hawks also stall quite excellently, giving you time to set up your Jace, The Mind Sculptor (WW) and Gideo Jura (ROE). In tight situations, Squadron Hawk is even worth 1 damage in the air! Squadron Hawk is a really insanely good card when you think about. Hand Advantage, mill advantage, plain, flat-out card advantage, a 1/1 flier all for just two mana. It's no wonder he chose it over Wall of Omens.
As for the fact that he plays no offensive five/six-drop as a finisher (aside from his Planeswalkers), it's probably because White/Blue really doesn't need them. White/Blue really started out as a set up deck, stalling out the game until you had enough threats to outwit your opponent. Once you got enough mana, you won the game by swinging for lethal with Gideon and Celestial Collonade. The deck is really about attrition more than anything. Stall creatures, counter spells, Boardsweep, etc. It's all about controlling your opponent; hence the terminology of "Control deck". I've seen variations of the deck that played zero creatures! The deck is in no immediate need of a huge finisher. In rare cases, sometimes it is even possible to go for a direct win by powering Jace up to ultimate.
I myself don't play too seriously (though you might think so judging by the above super-rant). I do, however, play competitive games with my buddies, we proxy the expensive cards so we can play seriously. I play competitive magic, but I play it casually and just for fun. Current deck is Blue/Black control, Guillaume style.
Edit:
Btw, Baneslayer, though dwindling in popularity, is one of the best printed cards in the current standard format, if not all time. The only reason it isn't being used as much because a lot of decks, Blue/Black control in particular, pack insane amounts of removal.