BMW used to be extremely good and very repairable/upgradeable.
They have clearly lost their way. Seems like a fundamental loss of confidence in their ability to produce leading technology, and instead feeling like they must defensively focus on blocking and extracting maximum funds from customers, both with costly "authorized-only" repairs and subscriptions for heated seats.
Sad
And even for their older cars, most parts have gone NLA (no longer available), sending prices through the roof if you can find them at all! At least Porsche and Mercedes have programs to manufacture new parts for their old cars...
(My E39 M5 was one of the last user-repairable BMWs, but it's getting very expensive. On the other hand, it's driving a significant market for regular people designing and building replacement parts, whether 3D-printed, CNC'd, or homemade)