This thread prompted me to have a look at mine again this morning, after its first thorough wash for a while. A 2005 bike with 30k miles, it is on its THIRD front cover - first replaced under warranty, second with a goodwill contribution from BMW.
This one has been on for over a year, and I took the precaution of smearing silicon grease all over the lower half on a couple of occasions. Don't know whether that's helped or not, but at least I feel like I'm doing something.
What I did notice is that it doesn't have unfinished faces where it's been machined. Maybe they have changed production to paint it after it's been machined? If so, credit where credit's due. Eventually.
(Also, dropped my bike for the first time today

- foot slipped while putting it on the centre stand, and it fell gracefully away from me. I couldn't stop it toppling, but did manage to lay it down fairly gently! Tiny scratches on right rocker cover, ditto right handguard.)