Really, it depends on your preference. Keeping every figure on the card is usually the option for toy collectors, because it's what they do. Sometimes they resell figures down the road, and they can get the most out of an unopened, mint figure. If you have an open wall that you can tack the figures up for display on the card, that's cool. However, leaving them on the card takes up a lot more room.
Some people prefer to have a display shelf where they can pose the figure. If you like that, take them out and pose them.
Either way, these will never be incredibly rare or valuable unopened (so I wouldn't not open it for that reason), as enough will be made to keep the value low.