I think this issue arises from fundamentally western ideas about what it is that are our most basic human instincts. We have certain instinctual needs, which, I'll agree, would seem to imply a hedonistic lifestyle when considered alone. However, many of these things balance themselves out. As an example, we have an evolutionary need to be healthy, viable mates, but we also have an evolutionary need to consume delicious food. Overindulging one need would inherently cause the other need to not be met. I would also add that the need to express kindness and compassion, and the need for positive social interaction seem to also be instinctual, and do drive us to act in ways that would not necessarily fit with a hedonistic lifestyle.

But how much do you dial it back?

The problem for me personally is that hedonism, while fun for maybe a couple of hours, inevitably leads to more complications and suffering than happiness over the next day, the next week or the next year.

A more measured, but peaceful life with many smaller (not big enough to be disruptive) happy moments has been my solution and I've mostly been satisfied with that.

The answer to the "why" is mostly fear, real or imagined. Why don't most people talk to a another person they find insanely attractive? Why do they not take time to understand a religion or philosophy very different from their own? etc.

Whatever floats your boat. As long as you don't force it upon others, I can't see why there should be any problem. The personal freedom for any individual to live as one finds the most happiness without harming others should be the goal of any fair/just society.