you know how many 3DS games were released in 2015 ?
answer : 104 (
you can count them by yourself)
considering that around 25 of those 89 has been released in 2014 or before, just 40 titles made for 3DS didn't chart, so I really don't see where are those "plenty of games" that you mentioned
the fact is that the market leader just had 100 titles released, very strange considering I don't think PSP had more title released compared to DS while the latter has always been the market leader.
last but not least, if you want I also have a list of titles which underperformed on 3DS, starting from Theatrhytm DQ and passing from Kenka Bancho 6, Kuroko Basketball, Yowamushi Pedal, Lost Heroes 2, Bravely Second, Super Robot Wars and ending with Medarot 9
this just shows that it's not only Vita which had underperforming titles, but it's the handheld market which is shrinking due to mobile predominance.