It's the reason to change that doesn't make much sense.
The reason was, that ASICs come around and you don't get (enough) bitcoins anymore on your FPGAs.
And it still doesn't make much sense to me, to switch the good cause that i'm donating to, just because I don't get (enough) bitcoins in return for my donation anymore (especially to switch to something returning even less than not enough).
Really, I feel like you are saying that someone who is motivated to make money cannot be motivated to donate. An FPGA would be useless for making money after ASICs are going in full force. If you make a couple of bitcents with one, but then have to pay out $5/month in electricity, you'd be losing money. Thus, if a person was solely profit-motivated, they wouldn't even turn it on after it became unprofitable. But, they might find benefit in using the device towards non-profit purposes.
To put it another way, doing anything for profit or non-profit nets a benefit. A person will switch from for-profit mining to non-profit calculating when the benefit for the non-profit activity exceeds the benefit of the for-profit activity. Obviously, it's a bit of an apples-to-oranges comparison, which is why each person has to decide for themselves exactly where that point is.