Southwest Rapid Rewards and similarly structured programs do not have this large overhang of unredeemed awards. Their account holders need not worry too much about devaluation of existing earnings. The downside is that you can't save up for anything more than a domestic coach award. It's a reasonable trade.

My strategy is to focus my flight earnings on Southwest and focus my Miles Buzz promo earnings on other airlines. This way I can burn both domestic and international awards.