The Macbook/Pro line fails in a spectacular way in a very key area (for some): Weight.
13" MacBook : 5.2 lb !!!
15" MacBook Pro : 5.6 lb
17" MacBook Pro : 6.8 lb
12" iBook : 4.9 lb
14: iBook : 5.9 lb
12" PowerBook : 4.6 lb !!!
15" PowerBook : 5.6 lb
17" PowerBook : 6.9 lb
Hmmm. The 17" is marginally lighter now. The 15"s are the same weight and the MacBook, with a larger screen, is a whopping .6 lbs more than the slightly smaller (and much less powerful) 12" iBook disguised as a PowerBook. (My shoulder hurts just thinking about lugging around that monstrous sized MB)
It's true though, those PowerPC chips were very heavy. The Intels clearly are flawed because they really should be much lighter. As you cleverly pointed out, Apple have clearly failed again with the MB and MBP.