Contrary to popular opinion, money doesn't automatically buy votes. Tax is a popular issue. This isn't like changing some minor regulation nobody has ever heard about. You can't bury the changes being advocated. And all the money in the world won't buy off every Grover Norquist from primarying Republicans who dare to raise taxes, however narrowly constrained.
This PR expands the Overton window around new tax rates at higher tiers, and that's good. It also helps defang the Grover Norquists by undermining their popular support.