2 things I notice:
1) there are a lot of default trusted suppliers, seems that this should perhaps be selected on install (trust all or trust local [geographic] or trust by selecting regions).
2) that unlike with cookies you don't get a record of how often a certificate (or CA) has been used - so I can't tell from looking at the certificate information FF holds whether I've ever used the dozen or so Turkish certs for example; this seems like useful information for users that's not being displayed. I only use Turkey as an example because I don't use Turkish websites [I barely know a handful of Turkish words] nor AFAIK any Turkish company's English language sites.
Why would I need to trust geographically and linguistically distant CA's by default? If I decide to do something with a .cn site that needs a https connection it seems that I should be able to get info like "these CA - you already trust - in turn 'trust' this CA which certifies the site you are accessing". That along with any warnings the browser wants to give on malware or phishing then would feed in to a decision to accept the cert and interact "securely" with the site in question. The sites I actual need secure transactions with are probably certified by less than a dozen CA; trusting hundreds by default then seems poor security practice [to this layman].