3.5 didn't fix serious flaws in the system. It 'fixed a flaw' in the WotC business model by charging full price (as opposed to a loss-leader strategy) for the core books, and flogging revenue out of a shrinking customer base with a rapid pace of releases calculated to appeal to players (since there's more players than DMs). 5e, of course, has reintroduced the flaw of slow releases that appeal to DMs (but kept charging full price). As a result, revenue has risen disastrously.
