After NBA2KLab ran some tests that determined Interior Defense doesn't affect shot contest ability, Beluba confirmed that shot contests are only affected by the Block rating this year. This is a change from last year, where shot contests were affected by the Interior and Perimeter Defense attributes.
However, Interior Defense is still utilised as far as a player's ability to defend post moves and not be beaten by them. Something to keep in mind when you're making your builds on Next Gen.
This makes sense and all, but as I said in a Twitter thread, my problem with changes like this is that they're kept quiet until after the fact. This is the kind of info that should be readily available as part of the game's onboarding and build system. Otherwise, it's left up to us to guess (or the folks at NBA2KLab to run tests and discover it), which means broken builds. Broken builds means starting over, and that means a higher chance of recurrent revenue. Again, "optional" is a relative term when it comes to 2K and microtransactions, in that the alternative is a long, unpleasant grind.
On top of the "many more fixes" patch notes in recent years, it'd be nice to see more transparency about these matters, the meta game, and the mechanics in general. In any event, there has been a change to the way those mechanics work, so it's something to keep in mind.