I think that a project can only go so far with a single list of features for supporters to bank on. With a tiered feature list, at the very least fans can decide whether the project/game can go further than it can be with the current feature list. However, the tiered feature list would need to be something compelling. What that is, needs to be brainstormed.
I will spend some time to think about it. Meanwhile, you can create a poll on what whether a tiered feature list is something the fans want or not. That should gauge how popular it will be if it is implemented.
Edit: With this implemented, risks will be higher as one could easily see Starbound got stuck in development hell due to feature sets that took too long to implement.