The Dutch M-346 situation is interesting, a sort of stealth mission creep.
It begins with saying "We need access to high-performance trainers", because they can afford only 37 (two squadrons) of F-35s and they're all single-seat. (The first high-g pull in a $100m F-35 is no time to find out that you just don't handle g very well.)
Next, you download some of your multi-aircraft training, so that your 2 v 2s are two F-35s v two M-346s. This requires some LVC training features and simulated weapons.
But then, if you have an Afghan/Iraq/Mali kind of operation with no air threat, you have combat-trained M-346 pilots and the aircraft is much less costly to deploy than the F-35.