I think it's more innocent stupidty/ignorance than anything else. I've had lots of stuff come in padded envelopes, but others packed immaculately. Most of the poorly packed stuff was simply a case of not knowing what they were doing. They didn't grasp the concept of MOMC in the first place and figured someone would open it anyway.
One dissappointing purchase I had was for the Tatooine Showdown cinema scene. No bids, but for mine ($4.99) and the guy shoved it in an envelope and overcharged on postage. Basically he was bitter because he lost money on the deal. well put a reserve on then bonehead.

No matter really, I was planning on opening anyway.
As a newbie (said the experienced old guy with a whopping 17 feedbacks) you're pretty much hooped. Leave neutral or positive feedback that gets the idea across.
great communication, fast shipping, packing could be betterwon't do much as I don't read positives anyway. Still, leaving feedback allows you the opportunity to respond as well. Wait for them to leave feedback. so long as instructions and payment were prompt, what can they say that doesn't look foolish?
Feedback is only a gauge, not a guarantee.