One interesting downside of this is that it will reduce the liquid ETH remaining for users who run validators. If Alice runs validators and puts in 100 ETH, she can run her maximum amount of validators (3) and will have 4 ETH to use on network activity. With this change, she can use all 100 ETH on her validator.
This becomes particularly dangerous in the case where staking becomes higher EV than any application (which could become possible with something like EigenLayer). This inactivity would be detrimental to the network.