I don’t think that the resolution was an attempt to justify the price. If that was the case, why go down in resolution from what’s available? Maybe if they were selling a 9k I would buy it.
Based off some back of the envelope math I did a while ago, I think Apple decided that 6k is the maximum usable resolution for a desktop monitor. At reasonable viewing distances you should be able to tell the difference between a 4K and 8k monitor, but you won’t be able to resolve every single detail of the 8k, hence 6k.
Unless you just make it bigger. They talked about being able to have 6 of the things and were showing dual monitors much of the time. Ultrawides have been demonstrating that there is demand for larger monitors. Most people who want a two or three monitor setup would probably be even happier with a single, larger monitor.
The bigger the monitor (or the more of them you want), the further you have to sit away from them. The further you sit away from them the less you can resolve all the details, making the extra resolution pointless.
If I were going to have multiple monitors, I would skip the Apple monitor and get a bunch of 4K panels.
Based off some back of the envelope math I did a while ago, I think Apple decided that 6k is the maximum usable resolution for a desktop monitor. At reasonable viewing distances you should be able to tell the difference between a 4K and 8k monitor, but you won’t be able to resolve every single detail of the 8k, hence 6k.