Well I sometimes don't understand when people obsess with Bitcoin being disconnected from the real world. If we agree that a currency should be a universal, liquid mean of exchange of wealth between people, when making a donation to the forum, the fact that the forum will hold it as BTC or exchange it on the spot (like if they were using Bitpay) shouldn't be that much of a concern to you.

As for what the amount is worth, after a transaction has been made, it's a bit silly to look back. Think of the 10KBTC pizza. Some people see it as a stupid act. But others don't, and I belong to them. If you want to look into the past, then do it right. If the pizza guy buys back the 10KBTC at market rate just after paying for his pizza, then do you still think it's stupid?

In other words, imagine that a member spends 50BTC on bitcointalk back in 2010 when it started, then buys back the 50BTC at market rate. Why would it be a question of "honor" if the forum decided to lower the fee in 2015? If the VIP didn't care to buy back the 50BTC back in 2010, that's his mistake, not the forum's or its future members', isn't it?