I'm not actually sure, because I feel like most of the things people do with SAP are very repetitive. Their UIs are mind-bendingly bad, but you mostly learn to do the 3 things you have to do all of the time, and then do them over and over again. I'm not sure how much having a nicer UI would make that easier.

It's absolutely not something you just randomly explore. I think that's a more interesting question: what sort of empowerment of employees could you create if the UI wasn't so terrible?

But SAP's moat is elsewhere. You put up with its terribleness because nothing else can do what it does. Beating SAP would require you to reach that, and do something else, part of which could be a nicer UI.

Every business software is at least as complex as the business process it models. That's the thing you training for.

Every detail of the business process is now explicit. Employees have to be forced to work according to actual process. You need quite a bunch training for that. Then employees will find shortcuts to make their own job a bit faster/easier, which will fuck up some cases. You need even more training for that and possibly some redesigns. And all you get from that is depression

No, because the training is about the core functionalities of those ERP systems, what action triggers what and so on. Training is not about how the UI works, this knowledge is gained on the job.