I had no idea people back-pedalled on their pledges. Then again I rarely pledge more than $10, and $3-5 is more likely. (I bought a MaKey MaKeykit via its KS, that's it. It already met the goal.) I'm still approaching KS under the PayPal tip jar methodology. I've never found the "merch" appealing enough to care, and it just drains money away from the actual project goal to deliver physical goods. I have enough t-shirts, and I don't hang up posters anymore.
The terms of service language is not accurate to its own spirit. This case (and probably others) has proved that back-pedalling in the last 24 hours can prevent a goal from being met, in aggregate. The math behind the scenes is looking at per-backer amounts, and that's not what's actually happening. They should revisit the policy.