The centrifugal gravity approach requires a massive structure - you need something like 200+ meter radius to keep rotation rates low enough that Coriolis effects don't make people nauseous (which would create a whole different toilet problem). Building a better space toilet is orders of magnitude cheaper and lighter than spinning up a habitat.

There are two issues:

- To build a centrifuge in space of sufficient size, you need to solve the problem of delivering a large amount of materials to orbit, because it has to be hundreds of meters in diameter at least.

- Such a centrifuge will create a gyroscopic effect, and the station will quickly become very difficult to control.

If people are going to live in space for any period of time then they are going to need gravity so long term, yes.

Ah a fellow Hail Mary fan :)

This does sound absurd at first, but how much gravity is really needed for collection? Is there any value in just a few hundredths of earth gravity?

Even with centrifugal "gravity" the toilets need to be designed for the worst case scenario (no "gravity"). Even if you could use a "regular" toilet the system needs to sequester and process the septic waste. That precludes even using the likes of an airplane toilet.

It's a significant amount of engineering effort, testing, feedback, and iteration to build effective life support systems for manned spaceflight. Long duration spaceflight is orders of magnitude more difficult.

Toilets are systems that can incapacitate or even kill the crew if they malfunction. In a low or microgravity environment aerosolized septic material can get in astronauts' eyes or lungs. It can also seep into electronics or other ship systems causing malfunctions. Even just clean water spraying into the cabin could be dangerous in microgravity.

You wouldn’t want to use a regular toilet even if you could, given how tight water margins are. Urine you can reclaim, feces not so much.