I think how they plan to spend/use the premine is a good question. I think a developer should be using some premined coins to keep the coin afloat as a backup plan in case it is ever needed and these actions should be transparent. I know it somewhat of a centralized way to work but I think it is worth the risk to make sure a coin has the best chance of succeeding. Some people act like it is a sin but I think it will prove to be a smart choice if the intentions are not to corrupt the market in anyway.
Isn't part of the problem with Devs keeping premise for any reason that you don't know what they'll so with it? Yes we want them to keep it to keep the coin afloat but how do we trust hem that they won't just dump in a few weeks when the price rises? Are there any devs left with good trust?