I'm not a game developer, so I can't really answer your question. But it's worth noting that most of these games are 32 bit on Windows too. I don't know if that's because of middleware or an actual desire to support 32 bit hardware, but regardless, it probably doesn't make sense to use 32 bit on Windows and 64 bit on macOS.

For non-games, a lot of the Mac software that was still 32 bit was using Carbon, which doesn't have a 64 bit variant. Carbon is old as heck, but if you're using it, there's no upgrade path other than a complete rewrite. That may or may not be worthwhile versus EOL'ing the software.

(As a complete tangent, I recently learned that Apple did once promise a 64 bit version of Carbon. The library was present in the developer preview of Leopard, and many devs began building with it. But then it was gone in Leopard's final release, and Apple never mentioned it again.)

Because no serious game developer expects a platform vendor to pull the rug out from under them. What benefit is there to an up-to-date port, especially when very few people already buy games on Mac? Most of these port projects were done 10 years ago, when Steam on Mac first released.

Except that has happened multiple times across the industry's history, specially on the consoles, it is a know business factor to take into account.

Console generations are a known quantity for both developers and consumers. A lot of people keep their old consoles around when they buy a new one.

You will never see Sony release a PS4 update that drops support for 2013-era PS4 games, at least not purposefully. If they did, people would be very mad.

Game consoles come and go, e.g. Saturn, Jaguar.

I did saw Sony drop the almost unused GL ES support on the PS 2.

Sure, but you're missing that it's worth the effort to maintain. Console platform sales are extremely healthy. Mac sales have never really been enough to support initial porting work, let alone continued investment.

I can only speculate as to each company’s intentions but I will say that it is not just a matter of “recompiling” to support 64-bit.

For example, one thing I noticed on the iOS side (when it went from 32-bit to 64-bit) is that pixel position rounding changed so you would see things like random one-pixel gaps where textures were previously adjacent, etc. These things add up, and a company might decide an older title is not worth fixing.

On the Mac side, the entire damned UI library was thrown out (Carbon), and it wouldn’t surprise me at all if games had been relying on it. That is a huge thing to just redo, and again I would not blame any game company for not bothering to spend the resources.