I think many other consequences has been weight in before deciding the punishment. As much as i'm frustrated that Montoya missed the chance to finish a Mclaren 1-2, i think he's been a victim of his own undoing. I do believe that Montoya has a small part in being whack from behind simply because he might have moved a little too much which left Pizzonia no room but to smack into him. In fact, True enuff Pizzonia should be a lot more careful when overtaking let alone unlapping himself, if the driver in front tries to be too fuuny, the barrier is the only place both of them gonna end up. Its dissapointing for Mclaren but thats racing.
As for Sato, he made a very honest mistake and apologised to MS. I really don't see why should he be penalised at all because race drivers make mistakes every race. Unless the mistake is deliberate whereby the driver behind purposely smack into guy in front or cause a totally avoidable incident, i really don't see why should the FIA punish Sato for missing his braking point or failing to warm up the brakes properly. Sato is definitely to be blamed for the incident but it doesn't warrant a 10 place penalty.
I'm a BAR Honda fan but i do think Sato is not qualified to be in formula 1. He's too clumsy, makes silly mistake, doesn't make good judgement during racing and isn't a very smart driver. Schumacher quite rightly said Sato drives like a kamikaze driver. I remember watching this onboard clip with sound whereby his engineers have to literally drive him thru the opening first lap corner. I do think its a bit shameful for the cream of the crop of racers to be guided thru the corner. Almost like baby sitting them thru the race.