The mathematics say that hacking hard on a layup drive to send them to the FT line to score becomes less appealing with good FT shooters.
On average on a play where the player missed the layup due to the foul, both the current and proposed rules yield the same average points per play. For a 75% FT shooter on average the play would result in 1.5 points under either rules.
But the chances for 2 points or 0 points jump way up under the new rules.
Doing that under normal rules, he has a (75%)*(75%) = 56.25% chance of scoring 2 points.
Under the new rules, he has one attempt to make 2points so his chances are 75% of scoring 2 points.
That is counter-balanced somewhat by an increased likelihood of scoring no points. Under normal rules, the player has just a 6.25% chance of scoring no points.
Under the new rules, it would be a 25% chance of scoring no points.
Now, all that oversimplifies because it ignores that most players actually tend to hit their second FT at a higher rate than their first one. That's going to drive players' personal FT% down slightly.
This is going to affect the calculus of how you defend shots. Worse, since they are changing back to 'normal' rules at end of game, then you change the way you defend during that stretch?
Personally, I do not like this change. I think there are probably other ways to speed up the game that don't change the way it is played on the floor.