Umm what? When was this? Scrubs always had a serious side that matched it's more goofy side. Besides, it would be kind of weird if the characters never faced any of the problems that actual doctors do.
The only reason scrubs is going downhill is, because it has been on for so long. There is only so much you can do with a show like this before ideas get too old. I still enjoy the show and will watch season 9..
Although you could see in the last season the show pushing (almost to an annoying level) the interns on us. I think Zac Braff was actually not in two episodes and it centered around the interns, and those were some of the worst episode of the season, IMO