Aside from Shakespeare characterizing fairies as generally capricious, as was said above, and cruel and kind on a whim (hence Oberon helping Helena is not inconsistent with him tricking Titania), I think it's also a matter of different sociological background. For the Elizabethans, boys would didn't belong with their mothers anymore after they made it beyond toddler stage. But I agree that's no help in a current stage production, but then they don't have to show the Indian boy at all if they don't want to.

Remember when we saw it coupled with the Barrie play? With the motif of the lost child and the separated couple given a very different twist there.

I've seen Oberon played as anything from Satanic and male oppressor to bark-worse-than-bite, it really depends on the production. Most that I've seen, btw, go for letting him and Titania played by the same actors who play Theseus and Hyppolita, which in one production made for a powerful moment when Hyppolita almost seems to recognize Bottom later.