Still, chances are, you will probably get the worst item inside. Wouldn't even think about spending MC on crates.
Sold a bunch of them and only opened the ones really good with the free keys given through events. Aside for the usual bad items, got some uncommon weaponry, several premium time and miraculously, only one mechbay. But that was just a one time thing from opening a lot of promising crates containing possible mechbays, MC or mechs.
So yes, opening crates is nearly useless.
