Since the value of Bitcoin has gone up drastically, relative to everything else, shouldn't there be a decrease in the total BTC donation amount?
No, theymos ever said the donation amount won't change no matter how far bitcoin price changed.
Theymos refers to bitcoin, not dollar.
I agree with your answer being correct; however, I totally disagree with it.
What I feel is a shame is that some listed donation badges are scammers from long ago and they are not removed. Any new company or legit person trying to get the badge simply can't because of the price of bitcoin.
Example: In the beginning of donations, I could donate 50btc for a cost of about $500. There is no chance I would donate $87000 today.
I can understand that it's nice to keep the list relatively short, but to expect 200 times the amount is absurd. When bitcoin hits $10,000 is it still going to be 50BTC, You know, only $500k to be listed and have the badge.
This blocks everyone from donating. That said, it also implies that bitcointalk.org is limiting the number of donations it gets.
I can understand the idea that the donation amount should be denominated in Bitcoin, but not that the amount should be static forever.
If you're determined to avoid measuring Bitcoin against the dollar in order to consider it a currency in its own right, then you could measure the value with the Big Mac Index, against gold or something similar. It's impossible to deny that the actual buying power of Bitcoin has changed, and therefore the donation should be similar as you're contributing to the forum for similar things that you were contributing for years ago.
Furthermore, many of the costs of the forum that we're talking about will either require the forum to convert it to fiat at some point to pay, or for the person receiving it to consider the fiat value of the coins in order to accept it. In either case the US dollar value is still relevant to what a donation should be.