Giving the top teams a reward for a good season makes sense. However given that there are 5 extra games which may not be balanced, there could be a 1-2 game difference in terms of the fixture in favour of one team or other.I actually like the OP's idea or something like it - it's basically the NFL type system which I reckon is OK. Gives the lower ranked teams the chance to pull off a Cinderella story, but provides some advantage to the top teams. In the current system, with all its quirks and the fitness levels requied etc. the advantage to the top 4 is too great.
One tweak I'd like, in a proposed or current system, I'd like to see the minor-premiers rewarded more. Currently there's nothing to be gained finishing 1st over 2nd which I find really strange.