I'm not sure I agree with the statement in the opening post, although there are students who pick subjects that they think would require less work to achieve a 40+ - I know of several people I did VCE with who used this reasoning to pick subjects such as Bus Man, Further, etc. (whether it's actually easier to score well in these subjects is a moot point).
I definitely agree that the system should be changed, though. I personally found that absolutely nothing from year 12 prepared me for uni, and if anything, that the structure of year 12 and the way things are done was (and is) detrimental to the ability to do well (that is, if you stick with the year 12 mentality in uni). IMO I find uni scoring a lot fairer and reflective of my efforts than anything in high school (plus, I find it a lot easier to understand). Sure, I scored highly in high school, but that was because I knew how to play the system. In uni (or at least, in my course), you can't play the system, and the effort you put in tends to be directly reflected in your scores. Now when I do well at uni, I feel like I've earned it and I feel prouder of my achievements, because I know that I worked hard. I struggled a bit in year 12 knowing I was scoring a lot higher than some peers who put in a lot more effort than I did.
There should be a system that encourages students to pick things that they're interested in and encourages them to find and explore their passions, rather than pressuring them to pick subjects that might reflect more favourably on their scores or require less effort in order to get a good score.
(Sorry if this went off on a tangent)