I would have preferred a sealed sheet for preservation and handling purposes--yes I know the shrink-wrap has a statement regarding not suitable for philatelic archiving, but if one doesn't plan to use the stamps for postage but rather for collecting/viewing, IMO, having the stamps sealed is preferable.
Over time the cardboard insert, which is not archival grade paper, will degrade: the acids in the cardboard will migrate to your stamps and discolor them.
The plastic wrap is not archival either. Not sure what kind of plastic it is. But here is what non-archival plastic can do: it may stick to the stamps, and when peeled off remove some of the ink/paper. Plastic that is bendable off-gasses until it becomes brittle. Those gases can react with the inks and/or adhesives causing them to discolor, or in the case of the adhesive, bleed out from behind the stamp.
If you want your stamps to remain "post office fresh" keep them in a cool dry place, out of sunlight. And only store them in archival grade materials.