First off I think its important to point out that DMs should be giving out considerably more than wealth per level. Wealth per level does not include the value of expended consumables, expenses, or the 50% loss rate from selling most items. I'd say 150% wbl should be a minimum, perhaps less if DMs are specifically tailoring items to the PCs in their group.
Its problematic I suppose. I would assume that on a given adventure characters are to receive equal shares? If so it would be hard to stick to wbl with characters at different xp totals or even potentially levels. I am also sure some games will take longer than others, whether due to pacing or simple post rates, and will thus give characters greater time rewards per level gained. Adopting HM's sensible proposal would lead to these slower adventures giving less loot effectively.
You also have the issue of value versus wealth. If we have two characters Hank and Eric - "It's a Dungeons and Dragons ride!" - and Hank keeps only items he finds where as Eric sells all the items he finds to be able to select exactly the items he wants then Hank naturally should have a higher wealth than Eric. On the other hand Hank might have found more appropriate items and not have needed to trade out, so its hardly appropriate for him to have twice Eric's wealth.
I am firmly of the belief that a character should not get less because their kind of preferred items do not come up much. On the other hand a frugal character who use what they find rather than sells everything to get exactly what they wan should probably be able to edge ahead of wealth per level. I know that in 3.5 play bards, and druids suffered from this fairly often - bards suffered a great deal because magical musical instruments were so staggeringly useless for their price and well intentioned DMs would give them out "for the bard".
So a tough issue. I'd suggest we don't operate by a hard and fast rule, but rather simply keep an eye on characters at level up and planned wealth in adventures. Treat wbl as a guideline and not worry about it too much unless a character seems to be well out of kilter. The main control should be that appropriate amounts of wealth are handed out in adventures imo, based on the intended level of the adventure.
We might also consider allowing PCs to come up with wish lists for items - maybe 2 or 3 at any given time. I find this enables DMs to better cater for a diverse group slipping desired items in where appropriate and helps prevent a magic mart feel where everything is sold off for desired gear.