If I'm ignoring it, its only because its not the be all and end all. This whole area of law was looked at by the House of Lords Appeal Court in a case called Miller v Miller. That case set out the current approach for Courts to follow.
In it, they decided that in order to achieve a fair settlement the Courts needed essentially to look at 3 areas, needs, compensation (for loss of earnings / opportunity etc) and sharing of matrimonial assets. In the paul&heather case, it was held that compensation and sharing featured little, if at all. So that only left the question of need.
I agree that their general life style in marriage was one of the issues to be examined, as there is a list of considerations that Courts ought to take into account when reaching their decisions, and that's contained in s25 of the Matrimonial Causes Act 1973 here and subsection (c) is for the living standards of the family during marriage to be one such consideration.
Clearly the Judge in this case is mindful of subsection (c) - hence his comment about the level of periodical payments for Beatrice. Also, even though PM had the potential for an extravagant and hedonistic life style, its not at all made out that this was the case - especially if you read excepts of his statements from the case.
And as they say, no matter how rich and powerful you are, everyone puts their trousers on, one leg at a time.