A lot depends on playstyle. You can gain wealth over the course of campaign mostly in form of random items (works of art, next-to-useless items), which means that if you want to buy useful equipment, you first need to sell the stuff you got (at a loss), effectively meaning that while you have a total 100k in gold and items, if you went to buy stuff, you'd be left with 60 or 70k to spend.

If players start at higher levels, it's fun to give them 50% of their WBL in form of randomly rolled stuff and see what they do with it. Of course, in game terms, it effectively it means they have less than their WBL would indicate, but "wealth" is just that, total sum of what they have, not "only the stuff that is 100% relevant to adventurer's class".