I just found this

http://searchengineland.com/google-tweaks-keyword-tool-and-t...

    The Traffic Estimator will now be available only to 
    advertisers logged into their AdWords accounts, because 
    it will begin using each account’s performance history 
    to come up with its traffic estimates. The standalone 
    Traffic Estimator is being retired.

If this is true, than it seems to reconcile all points of view. Traffic Estimator gives different information based on past performance of the adwords account, so if you've had unsuccessful campaigns in the past, it assumes you'll be unsuccessful in the future. It does this using the success rate of the account itself, rather than looking at any particular landing page quality, which it can't do, since you're never asked for that information.