The problem is that it's really easy to create a dent/crease if you stuff the frunk too full and then attempt to use force. And in that case, it *is* the consumer's fault. I've caught my kids before getting ready to apply Popeye-the-Sailor-Man-Spinach-Mode force to the frunk to close it when they didn't put our cargo in it correctly.
At the same time, I use the frunk very regularly and I don't have dents or a crease. You need to ensure that you aren't creating too much leverage to create the front-lip crease, and you aren't doing too far back on the panel to put the dent in it.
And for those who say "there's a problem", I disagree. It's the nature of a hinged panel like this. Yes, it would be nice for Tesla to add a motorized latch, perhaps they'll be doing that in the future, but I don't think it's a design defect at all.