The slip rings are not in the middle of the motor, they're on the butt. I know car makers don't always try to make things serviceable, but it'll be hard to make it hard to replace. Probably the only issue will be needing to remove other parts first to get to it, if anything.

That does not sound worse than replacing the spark plugs in a Subaru engine.

They do not need to be half disassembled. That's hyperbole.

Brushes are usually easily assessable from a cover at one end of the motor or dedicated brush holders accessable from the outside.