I can't comment on what the US saturn cases are like as I only owned PAL versions, which were black plastic with cardboard on the outside. The glue would let go after a while which made them equally crap, but in a different way.
I've gotten rid of most of my Saturn stuff, only kept 2-3 of my favourite games + the console.
The US Saturn cases can't be any worse than the PAL Dreamcast cases, you just had to look at them and they would break!
I agree the battery was either a silly idea or a smart idea, it forced people (like myself) to buy the cartridge otherwise you'd lose all your save data. I guess the reason Sega did it was to save money, flash memory was worth a fortune back in 1995.