It's a big deal for the car companies because they get money when they lease a car. Whether or not they pass any of that on to the customer is up to the car company. In typical capitalist fashion, two of the biggest lobbyists for the lease change were Hyundai and Kia - both of whom did not pass any credits onto leasing customers under the prior tax credit program. They want to get paid by Americans to lease EVs in the US.
I've seen nothing in all this that suggests that MSRP or income requirements would be affected. If they were, then the change would encourage the wealthy to lease expensive EVs, which has nothing to do with encouraging the adoption of EVs.
The whole incentive program should have been structured around mileage. Each 1,000 miles driven gets you a $75 tax credit until you reach 100,000 miles. This means that the more efficient an EV is, the better the return for the user. It also encourages use of EVs over simply buying one. It also eliminates any issues of leasing or buying. If you rent an EV for a vacation, you still get a tax credit for the miles you drove.
Such a program would be harder to regulate (verifying reported miles), but I think it would focus on the goal, which is to get people to transition to use of EVs to get around.