From someone who worked retail for years:
Please ask an employee to open a box for you.
If you do decide to buy, PLEASE buy the one in the box that you opened.
I can't count the number of times a customer would open a box, take out the item, shove it back on the shelf (all taken apart) and pick up a new one in a pristine box to purchase. I've seen 5-10 boxes of the same item all opened and taken out sitting on the shelf - apparently the first 4+ weren't good enough to base a decision.
As for why they don't have them on display, most often it is because they don't have a place to put the display without reducing the number of items that can be out for purchase (and then they get complaints because the customer can't find the item in a box to purchase).