I also question the decision to only include the special features BD rather than including a BD copy of the film as well. It can't add THAT much to the cost of the package, can it?
I agree on the 4-track, but 4K scanning is expensive and Synapse is a small company. You do what you can within the confines of your budget. Many Criterion releases have been 2K scans and look gorgeous. In a perfect world, all 35mm productions would be 4K scans and large format either 6K or 8K.