I like the expected wealth guidelines.
As a DM, I'm there to help make sure everyone has fun. None of the players I game with have a lot of fun if I'm constantly skimping on the treasure. I don't follow it to the letter, but I sure as heck use it when creating pcs above level 3 or 4.
I find it to be a valuable guide to keep my parties in line with the challenges I anticipate giving them.
Here's the thing, though: an expected wealth level being met tells you literally nothing about what challenges a party is prepared to meet.
So the rules say that a character of level X should have a wealth of Y GP
Adam has, literally, Y GP.
Barbara has Y GP carefully divided into appropriate gear, weaponry, and other combat effective assets, with a small reserve of gold on hand for day-to-day use.
Charlie has Y GP invested entirely in turnips.
They all meet the wealth-by-level guidelines.
Adam is prepared for any challenge he can buy his way out of, but is unprepared for immediate action if he cannot shop first.
Barbara is prepared for any challenge she can fight her way out of, but doesn't have the liquid assets that Adam has.
Charlie is entirely unprepared for any challenge that cannot be overcome by having lots of turnips.
If the potency of necessary equipment a scales up at a predictable rate, then it's perfectly reasonable to have guidelines for what a higher level character should be given as starting equipment.
However, such rules need not in any way be tied to wealth.
I myself would prefer a solution where the rules for what equipment a character gets to start are viable at all levels.