Not that I like the whole Extended Warranty restrictiveness, but I suppose the argument goes:
"I've got a rattling noise from my suspension" which is then followed by all manner of forensics by the OPC, only to discover that you've got bell and hat aftermarket Type III Brembo floating discs that do sometimes do this. Who then pays?
I can even reconcile myself to the N-rated tyre argument: we now know that Michelin PSS are NOT an ideal match to the 997. More 'grip' maybe, but some slight loss of handling precision at high speed, and a float that appears not to be present with the ('inferior') PS2. Again, who would pay for all the time-wasting to get to that conclusion, including all manner of geo checking, inspection etc.
I personally do NOT think the original discs are man enough - I've done 12k miles and mine are clearly on their way out - they're vibrating. I'd love to change to GT3-typre floating steel discs, but looks like I'm stuck.
Of course, the sneaky question is "could I get away with non-Porsche branded, but genuine OE-manufactured discs or pads?" Most likely, yes, but given my mileage, do I really want to bother winding up the system for the sake of saving a couple of hundred quid every 4 years?
FWIW, I DID take up with my OPC dealer principal the extortionate mark up on the pollen filter - £12 for the MANN one and £75 for same MANN one in Porsche box. My argument being that you FORCE me to use your parts, but then apply a truly extortionate mark-up, which I described as a 'restrictive practice'.