Can ABC Please Dive Deeper into its Guest-star Pool?

Coming in fall 2008: a new ABC sitcom starring Eddie Cibrian and Josh Randall as wacky roommates! That's my prediction based on the omnipresence of those two TV journeymen as guest stars for the Alphabet network.
Within the span of a week, Ed alum Randall reprised his Men in Trees role of Annie's loutish brother (in an episode taped last season, I grant you) and also surfaced on Private Practice as Addison's would-be (if not for his propensity for probing his posterior...) beau. Cibrian, meanwhile, recently played Karen's ex-husband on Dirty Sexy Money, and this week can be seen pitching woo at Samantha Who?
In a similar vein, ABC tapped Sara Gilbert to play a convenience-store robbing mom-to-be on Private Practice mere weeks after the Roseanne vet visited CBS' Big Bang Theory. (That was the PP episode which went for the sweeps month hat trick: Name Guest Star, Emergency Baby Delivery and Hostage Situation.)
Setting aside my opinions of any of the aforementioned actors (Randall's appeal eludes me, frankly), the point I want to make is that turning to the same faces again and again robs a guest-star role - as well as the actor filling it - of any "specialness." Instead, it comes off as "so-and-so's latest in a series of paychecks." You almost suspect that SAG would go public with a plea that other actors get called upon for work. Much could be learned from, say, The Closer, which draws from this terrific roster of character actors who sometimes you can't even quite place, and yet the casting is always dead on.
Not to beat up on ABC, but perhaps this season's utterly strangest bit of guest-casting came just days ago on (again) Private Practice. Joy Lauren, whose Desperate Housewives teen just gave birth, played... a teen who just gave birth. Yes, really. In all of Hollywood, the only young actress ABC could find for that two-scene appearance was one who is in a near-identical story line on one of its own shows. Not to take anything at all away from Ms. Lauren, but it was such an unbelievable casting choice that I had to repeatedly check with my wife: "Is that really the gal who plays Bree's daughter?" Only a knowing wink to the audience could have saved the moment. But it never came.
If only guest-casting was the worst of what ails Private Practice - but that's a separate blog entry all together.