Excuse my ignorance, could you tell why it's useful to remove the certs from a PC. I've heard about root certs a couple of times already but don't understand what they really are.
"This particular website is X". And it can back this up with all sorts of fancy math.
The problem then, is how do you know that the particular certificate is correct? I can go through and make a certificate saying that i'm santa clause. How you get around that is by using another certificate that you already have, and using that to certify the websites certificate. Ie. if you trust godaddy (or the hong kong post office), and I have a certificate saying that i'm me, signed by godaddy, then you can trust that i'm me.
The collection of certificates that you trust are then called the "root ca", and having random certificates there is a problem because if one of them was to produce a forged certificate, you'd never know about it. ie. by adding in untrusted certificates to your root ca, you lose trust in the whole certificate chain of trust process.