I am not sure I understand why the material of the case would determine cleaning or not.
Has to do with the flexibility of the material. Brass is "stretchier", and when fired it expands against the chamber walls and completely seals it off. Steel is not as flexible and doesn't seal the chamber quite as effectively causing crud to blow by the case mouth. Aluminum will stretch a little bit, but it isn't as ductile as brass or steel so it has a tendency to tear. That's why if you have a loose chamber, you'll wind up with split aluminum cases.I am not sure I understand why the material of the case would determine cleaning or not.
If you don't reload and the price is right, aluminum and steel are just fine.
Contrary to internet BS rumors on gun sites, steel ammo doesn't destroy your ejector and aluminum is not 'dirty'.
Steel rifle ammo is not just for sloppy commie guns. I've run many, many cases of Wolf and Silver and Gold Bear through my ARs without issue. As have many other people.
The 'lacquer' thing is a fairy tale and I'm pretty sure that the mild steel of the case is a lot softer than the the rest of the upper receiver. It's also pretty accurate - it's not match grade but it's 80% cheaper than match grade ammo.