Lootboxes influence how the game plays. Inclusive characters is [an issue of] perception, not gameplay.

Opposing inclusion [of other kinds of people] is different from opposing mechanics.

Why are they getting away with it?

Established culture, critical mass, and platform ownership.

Steam is an online platform owned by Valve. They have ToS and a Code of Conduct. Those are published, announced baselines you can compare and report against.

Churches are not all the same, and are generally not on a platform with authority you report them to.

You’re asking for public shaming. Which can and does [sometimes] happen as bad press, protests, and prosecutions. But generally, it’s more difficult and higher risk in the real-life public, and less likely to succeed given their established nature.