1984 Mint Set. Yellow Laminate Both Sides!

I know dealers definitely use the "yellow-plastic makes it worthless" line if you sell one to them over the counter. In all probability, those same dealers will slice open and sell separately any coins they receive in yellow-plastic sets, and get far more for the coins sold separately than for the CV of the intact set.

From a conservation point of view, the yellow plastic won't hurt the coins. If the coins still look perfect inside the yellow plastic, they might as well stay there - putting them in anything else might subject them to worse conditions.

So: if you plan on selling them soon, or if you want to keep the coins with your other coins (in 2x2s for instance), or merely if looking at coins through yellow plastic bothers you, then bust open the set and do what you like with them. For medium to long term storage, the set plastic will protect the coins just as well as anything else, so I'd recommend keeping it intact.