@MaTu94
that might be true, but it's also one of the faster methods.
For example, importing superior crops for farming won't pay off in a few years time.
Animals, on the other hand, thanks to cross world-hopping could pay off just by slaughtering the animals.
The best thing would be to do a little of everything.... but if they help too much it might cause other problems too.
That said, just like
@Iume mentioned transporting living creatures is a huge risk for pandemics.
If they are not really really careful or have some magic to prevent it, it might turn out like when the Spanish invaded the Incas.