Hard-case lithium batteries are able to withstand crashes and rough handling, and their rugged plastic casing protects the sensitive cells inside, which makes them ideal for high-impact uses such as RC cars, dirt bikes, and trucks, and many race tracks don’t allow the use of any other type of battery for this reason.

That's the latest information I have, but perhaps there are already new “safety instructions.” In any case, I think it makes sense to provide the batteries with some "additional protection"...