Personally, I seem to be one of those who dislikes the DLC. I understand why DLC is sometimes necessary, but it can hurt games too. Generally, I think:
#1: Regardless of mission packs / visual packs etc., Parts, max part count, max size etc. should not be behind a paywall. Everyone should have the ability to use all the bits.
#2: Before developing DLC some other game features should be added. Mainly, a non-laggy multiplayer.
#3: DLC should always expand on, add to, or improve existing mods etc. The whole point of DLC is to add content premium enough to warrant a price.
BTW- I did purchase the game before the deadline so this response is unbias in that aspect.