People just want to see that their money is doing something.
which is the problem at it's root.
It the "backers" (better word than buyers) do not have the mentallity to understand they are giving a donation (with a possible reward) and not actually buying a product, things would work better (less hassles with "refund demands" or "its broken" comments).
I place the issue mostly at the feet of people that started this whole buying in for beta access as they did not take the responsible path of keeping the terminology along the "dontation path" but instead pushed for more money by swinging/wording the delivery to be more like a share trading where getting in early, before release, was a "sure thing" and even "exclusive club" spin on things.
That being said, I tend to agree that the charging higher than any retail price gets rid of a lot of the "bargain hunters" and complainers, it does also turn people off in terms of marketing (ie: come out with a lot of hype, get people interested, then not deliver for a year). No one is going to be talking about it when it does actually get released as the audience is burnt out already. This I suspect makes for less actual sales at release.
There is no real way to win short of only allowing alpha/beta access to the true diehards (several $100 to access ect). Of course, then that also means only allowing early access to the general public a few weeks or a month before the actual release (Team Fortress and steam ect) but it does not help when after development money.
Some examples of the sales and forever beta of one game I was looking at was "Folk Tale", Early access since 30 may 2013.
One of the ones that did the high starting cost (turned me off after all the hype) was Plantary Annihilation. IIRC beta access was $100 USD.
Of course, going the several $100 early access path might mean not enough money to even make it work while to provide feedback to those people if not enough sign up.