IMHO it would be a good idea to have an additional option, either as a global option or on a per-server base: It should be possible to restrict the lifetime of a cookie, i.e. to convert a cookie that has an expire date to a session cookie* automatically. This way, a user can visit sites requiring enabled cookies without exposing to much of his privacy. * or even less: e.g. half an hour Sorry if this idea is not new. I scanned thru the open bugs quickly and didn't find an appropriate one.
Feature already exists. So marking this request as invalid. However there is no UI for the feature. See bug 53354 for the missing UI.