When it comes to MOC or MIB things, generally, I'm a little kid. They are toys and therefore meant to be played with. That's what they were created for. I can't help but feel sorry for the poor little things suffocating inside boxes, bags, and bubbles, never knowing the loving caress of human touch ...
Yes, I tend to personify inanimate objects a bit much, but it's more fun that way.
It probably stems from receiving several special edition Barbies as a child, and being told I couldn't play with them. My logic of course was "But she comes with a brush! She's supposed to be played with!".
I've yet to buy a MOC, MIB G1, but if I cam across one for a decent price, I'd probably buy it and open it. I imagine there's nothing else quite like being able to open that vintage pony for the first time, knowing nobody else ever has ...
I'm rambling.
Long story short, I'd say open herrrrrrr!