I guess the other way to look at them is are they toys or collectables?
I can't imagine there's any way to not regret opening a toy when, a few years later, you see the same MOC figure selling on ebay for 5 times what you paid.
But then I own MOC figures that I could sell for a good profit...but then the toy wouldn't be mine. And that's how I view my MU toys. I love the collection. It fits the comic universe perfectly to have a large group display with various teams collected together.
Plus that damn Galactus only makes sense when you stand it next to Thanos or Hulk. Resting carded figures against a boxed figure isn't quite the same!

I rarely open anything. I like'em MOC, because then it's always "new" and gives me the same feeling of when I first saw it in the store on the shelf. But to each his/her own! :)

I would say for starters, damn your lucky to own such a badass figure, 2 would be anything of mine you want in consideration for a trade? 3 or how much flow is going to be sucked out of my bank acct, you sweet temptress of plastic crack! PM and we can get into further debate as far as price and trades.

i have all my MU out of package, mostly cause I have the room for display over my desk. I dont care about the monetary value, only the aesthetic. Howevor, the avengers and FF three pack i picked up are staying in package cause they look nice. Cant wait for my sentinel tho lol.