Right now, I won't trust it that much.
Further, there's no room for decreasing my trust in a cert based on the length of the chain, or who's on the chain, or anything like that.
The whole system is structured to produce a 100% certification of trust, or a 0% certification of trust. This has the consequence that when the system is compromised in the way that you talk about in your last paragraph, it doesn't degrade; it falls apart.
It's not that robots from the future might compromise a cert, and going to something so fantastic in the light of the real threat of sovereign governments and the proved threat of compromised root CA certs (proved as in "you could buy this device for real money and have it really delivered to you") is a rhetorical unkindness. It is that nobody can any longer claim with a straight face that the system is 100%, and unfortunately, with SSL that leaves only one alternative.
Compare with the semi-mythical "web of trust", which would have ways of dealing with this that doesn't violate the very mathematical foundations of the system.
Moreover, even as a sophisticated user, I have to observe that I actually do not trust a single root certificate in my browser the requisite 100% that is necessary for this whole system to work. I can not assign a 0% probability to any of them being compromised by a hostile force, especially when the hostile force isn't necessary a random hacker but may be a sovereign government.
So, while your point is totally correct, it should be pointed out it isn't really a defense of the current system. (Which you may not have intended it as, but I have seen others use it this way and it's worth pointing out.)