You're mostly right, the build point system strongly encourages high powered characters, and it's fair to assume that's a design choice rather than an accident(regardless, they didn't change it with SR4A, so they're happy with it at least).
It's actually inefficient to start the game with a stat at natural max. Raising an attribute from 1 to 5 costs 40 BP, and 70 karma. Thats a 1.75 karma to BP ratio, averaged out, while raising an attribute from 5 to 6 costs 20 BP or 30 karma, which is a 1.5 karma to BP ratio. Thus it is more BP efficient to raise raise attributes up to 5, but not to 6(assuming human). In fact, it's just as efficient to change a 2 into a 3 as it is to change a 5 into a 6. Just avoid 6's at creation in the BP system, buy them with karma.
Skills are another matter, you should always have your one at 6 or your two at 5(the one at 6 gives you a better exchange rate), and put the rest of your important skills at 4.
Honestly, I prefer a heavily modified karma creation system.