On "Grey's Anatomy" and its disappearing characters

According to Michael Ausiello in his EW column, Katherine Heigl and TR Knight are both trying to get out of their contracts at the end of the season.

This made me think about what has gone wrong over there at Grey's, and this is what I've come up with: stop rotating around the cast members! In it's inception, Grey's was an ensemble drama, and without a doubt, the best part (and the entire point) of the first season was the friendship between the five interns. Addison was a welcome addition, and Callie provided a semi interesting foil for George. Otherwise... stop adding cast members! Once they messed with that ensemble is when the show really started to go downhill and veer off its course. And now, two of the original cast members are so disappointed with the fact that they're being ignored, that they want to quit.

Perhaps the solution to their problem of original cast members leaving and new ones not lasting is that they need to stop trying to add new ones, especially "quirky" ones. Give the show back its heart, and then you can give the characters love interests, if you must.