To a degree, I do the same thing. Buy slabbed cards when the price is right and set the player free! Only to end up in the particular set I am working on at the time.
However, I did get some of my cards graded and will do so in the future. Just to sell though.
The thing I do differently when it comes to cracking the cases is I take the entire top portion of the slab off. Heavy duty wire cutters do the trick for me. I find it makes it easier to release the card from its surly bond of containment. And indeed, watch out for flying plastic.
Cheers,
B.T.