I agree it's not worth the hate, but in my opinion SI units are much more convenient.
Using your own example, miles vs kilometers may not feel like a big difference, but the fact that you have proportional units (mm, cm, m, km) for any possible distance has the potential to save you a lot of trouble. Having completely different units for the same thing (land miles / nautical miles for distance), usually not proportional between them, is less practical than the SI at every level. Not only for an engineer but also for home owners and almost everyone of us.
I understand why there are some places in the world where they still use systems other than the SI, mainly for legacy reasons. But I think the practical benefits of a more coherent (and standard) unit system exist not only for the engineer.
Using your own example, miles vs kilometers may not feel like a big difference, but the fact that you have proportional units (mm, cm, m, km) for any possible distance has the potential to save you a lot of trouble. Having completely different units for the same thing (land miles / nautical miles for distance), usually not proportional between them, is less practical than the SI at every level. Not only for an engineer but also for home owners and almost everyone of us.
I understand why there are some places in the world where they still use systems other than the SI, mainly for legacy reasons. But I think the practical benefits of a more coherent (and standard) unit system exist not only for the engineer.