First off, if a vet thinks neutering will change aggressive behavior you should look for a new vet. That is such a discredited myth. If she doesn't know that what else doesn't she know?
When considering whether to neuter, I'd suggest you check out the link below. It has scientific research to dispel many neutering myths.
It's a brief but very thorough booklet discussing the pros and cons of neutering/spaying, more science based than anecdotal.
There is definitely less societal compulsion to spay/neuter in Europe.