Well, the disproportionate bodies are just a stylization. And the younger characters, I assume, have bigger heads compared to their bodie's because real baby's and young children have large heads. It's just a way to help represent the characters ages.
I never had a problom with the size of Frankie's neck. It never struck me as obscure. The only thing about Frankie that doe's is her leg's. And that's only on rare occations like when she was in her bathing-suit laying on the beach in "Squeeze the Day".
I think that maybe the reason I don't really think about these things is because I take the characters (As real as they are) as cartoon characters. I guess I just never questioned these things after haveing 22 years of cartoon watching under my belt. Plus, exzagerated faceal expresions are funny. I always laugh when Bloo's mouth is 2/3' the size of his body.
