That is completely illogical. With that logic a pizza would still be 10,000 BTC because it would be 'unfair' to the guy who bought a pizza for that much, when that was the price of a pizza at the time.
Deflation is a thing, and I would enjoy hearing the opinion of a donor who genuinely believes that their donation of $50 in 2012 is equivalent to someone donating over $100k today.
The donation amount was not 10 dollars but 10 bitcoins. The price was in bitcoins so that's what people paid. We can argue all day long about how fair/unfair it is or whether donators will be annoyed if it was changed but it's irrelevant as theymos has said he won't lower the price. It would be much simpler to just create additional Silver and Gold membership levels instead with additional perks and fix the value in fiat and then they would become the new vip/donator ranks and no one can complain then.