I went backwards...
When I GM, if you multi-class, you multi-class for life... If you start as a Fighter, pick up Wizard, and then go Rogue, you are a Fighter/Wizard/Rogue. If your levels aren't advanced in each class, then maintaining skills in the no-longer-used class will slow your advancement in the rest.
This isn't a bug; it's a feature!
This isn't a restriction; you can be whatever you want... including a cherry-picker. If you just cherry-pick the classes, however, you will suffer the penalties.
I don't think players really want a Fighter/Rogue/Bard/Wizard. I think what they really want are certain of the abilities that those classes bestow. Since I also don't use Prestige Classes, I am more lenient in allowing PCs to acquire special abilities through other means...
Thus, I see fewer multiclassed PCs (except in the rare cases where someone really wants ALL the abilities of BOTH classes), but I do see Fighters and Rangers who can detect traps above DC:20, or who have different class skills, or other such abilities; so it all evens out.
I guess I don't see the "Character Classes" as building blocks, but as life choices. YMMV.
When I GM, if you multi-class, you multi-class for life... If you start as a Fighter, pick up Wizard, and then go Rogue, you are a Fighter/Wizard/Rogue. If your levels aren't advanced in each class, then maintaining skills in the no-longer-used class will slow your advancement in the rest.
This isn't a bug; it's a feature!

I don't think players really want a Fighter/Rogue/Bard/Wizard. I think what they really want are certain of the abilities that those classes bestow. Since I also don't use Prestige Classes, I am more lenient in allowing PCs to acquire special abilities through other means...
Thus, I see fewer multiclassed PCs (except in the rare cases where someone really wants ALL the abilities of BOTH classes), but I do see Fighters and Rangers who can detect traps above DC:20, or who have different class skills, or other such abilities; so it all evens out.
I guess I don't see the "Character Classes" as building blocks, but as life choices. YMMV.