All the things
I think they cared about it mainly from an arbitrary benchmarking perspective. Pretty much the same thing as "I have to cut the 30!!" in any other game; a goal that they know is achievable, but is not necessarily anything special about it other than it being a number. If they really wanted to pursue IGT, there are a number of optimizations and things they would have to go back to, such as Murder Beam. The "traditional" route (used in Zoast's 44:08) just happens to be fairly good for both real time and game time, though apparently not ideal for either.