Nickel handgun brass came from the era when police (and about everyone else) carried rounds in leather belt loops. The chemicals used in tanning the leather would, over time, corrode brass cases left in the loops. Takes longer in dry places than in wet ones, but does happen.
I, personally have never found nickel cases to be any more prone to cracking than my brass ones. Both seem to fail at about the same rate, in the same calibers and load levels.
If you have "good" nickel cases, the nickel doesn't crack or flake off. Of course, the only way to know that is by using them over a period of time. I've got .38 and .357 stuff from the 60s, still going strong.
I had some .45acp stuff from Federal bought in 1980 where the loaded rounds were chambered so many times over 20+ years there were brass stripes worn through the nickel. Never any problem with them (and never any bullet set back, either)
One of the advantages of having nickel cases is if you have both a rifle and a pistol in the same caliber (such as .357), and you load one level of loads in brass and another in nickel, you can easily tell which is which at a glance.
I would never toss nickel cases just because they are nickel. If you don't want them, SELL THEM, someone will be happy to buy them, and if they are range pick up, its all profit, right??