There are better adjustments than just scrapping an income limit entirely.
the marriage/partnership penalty should be eliminated.
there should be a phase-out of the benefit instead of a strict cutoff. As you earn additional money over the threshold, you should not end up losing money because of the loss of a benefit. A phase-out reduces the amount of the benefit as income rises, adjusts for taxation, and eventually reaches zero benefit. So at no point does a persons net position decrease just because they got a raise or a bonus.
its a basic concept of good tax and benefit policy because otherwise you create disincentives to work. Calculating the phase-out tables isn’t even that difficult.