While I do agree, Dash has another variable related to the coin supply: the burn rate. Because the number of proposals per month will change it's harder to predict the final coin supply. One might argue that allowing the DAO to resuscitate burned coins would lead to a more predictable coin creation rate.Don't mess with coin creation. Predictable coin creation (inflation) is what allows crypto to maintain its value.
Having said that, we could still get a pretty good idea of the coin supply by watching the trend of the number of proposals submitted each month, so it probably doesn't really matter if we bring back burned coins!