The point is that once this seed trust has been established, which ideally would need to happen only once in your lifetime (given proper sync/backup facilities), you gain actual control over who you want to delegate your trust to, if at all. On a site-per-site basis.
If an american, a chinese and an EU database independently agree on a fingerprint for a site then that would be an actual trust indicator. Very much unlike the perpetually compromised zoo of certificate authorities of today.
And obviously once there's a market for plugins you'd quickly see plugins going far beyond what we get to know today (read: essentially nothing). There could be subscription-based plugins providing detailed information about the remote party, down to credit ratings, company history, you name it.