The real question here is; Why can't a cleric get optimal divine casting DC's without multi classing? Splashing FVS on a cleric? Is this in hopes of generating more FVS sales?
This was not an issue before, maybe this system is very flawed and ill conceived? Maybe its just barely confusing enough to keep people from realizing how messed up and limiting it is? So busy playing with a tiny part of a new toy, that was always there, you just didn't see it, you have not yet noticed how much of the toy is missing or broken.
So many good points on this thread that show the limiting nature of the tree system. Now everyone is mixing all the "sub classes" to try and get what they would have had in the old system, minus some new candy, but plus massive customization.