Another solution would be to have a interest or no interest option at the beginning of the game. Don't like interest, you don't have it now. problem solved.
"But other people still can buy interest and even though it doesn't effect me in any way. I want it gone. STOP LIKING THINGS I DON'T LIKE!"
And thank you for breaking your own map to give these jackasses what they wanted. Didn't the map get played even less after this was changed? Your only hope now is when the new custom update comes and if it's going to be like we think, you're going to have a swarm of players begging for the interest increase.
By the way, usually pissing off the majority to appease to the few is a -really- bad idea.