While I agree with the fact wearing a helmet should be the owners/riders choice,I am also going to say I am still here because of one.
IMO its like this....
While many feel the freedom of no helmet may be their cup of tea,its not mine.The way I look at it is if you feel your head is worth nothing to you,then you go without a helmet.I have been across the hood of a Honda many years ago and smashed my skull on a sidewalk curb due to a uncaring person who turned in front of me with no use of their signals.That laid me up for a long time and kept me off a street bike until just recently again.Wearing that Simpson way back then saved me and gave me a chance to one day ride again,there will always be a helmet on my head,no matter what the weather or laws state.
I'd venture to say that while the Delaware law may seem a bit odd to you,its probably a liability deal and their way of covering their rears.