I rarely see imperial hex. Many Allan key set still come with imperial sizes but all contemporary products and screws come as metric now (in my experience in the UK).

Even with the metric there are still many sizes needed, which I agree is frustrating. However, it ensures the correct bit size is used for the correct screw. Unlike Phillips, pozidriv and slotted. It also limits the amount of torque that can be applied to a screw that is proportional to the screws thickness.

The prevalence of low quality screws and tools for hex drives is because they are cheaper to manufacture. Its unfair to reduce the rank of the drive mechanism for that. If the average hex screw and driver were built with the same quality of materials as the average torx this would be less of an issue.

I would recommend you use a screwdriver with hex bit heads instead of Allen keys, if you need to use hex screws a lot. Much more pleasant experience and much less likely to bend and twist like Allen wrenches.

Well designed things and screws should come with appropriate drives. I wouldn't recommend using a wrench on internal hex drives. If they needed high torque they should be external hex like a traditional bolt. Only external hex, large torque and large internal hex should be applied with a wrench. Other drive systems should be used when hand tightening is all that is needed. I've learned the hard way tighter isn't always better.