This isn't wrong, but rationalists sometimes take it to unhealthy extremes and need to do it less. I've often seen the argument that since you choose how to react, you don't have to react when someone is being insulting. This puts the blame on the person who doesn't like being insulted rather than on the person doing the insulting.
We need to recognize that some reactions are appropriate and need to be treated as such, even if you could choose not to make them.
You do not need to react to an insult the instinctive way (e.g. yell at them, or attack them), but there are other ways to react, such as say calmly "please do not talk to me that way", or make a note never to invite the person again, or tell your friends that the person was rude to you, etc.
The thing you mention is in my opinion rationalization of conflict avoidance. It is perfectly okay to suppress the instinctive reaction in favor of some other reaction, but sometime people simply avoid reacting because they are afraid, and then rationalize it as "responding rationally".
Also, the advantage of natural reactions (e.g. telling the other person loudly to stop insulting you) is that they are legible for people around you. So sometimes, the proper reaction is to do the same thing you would do instinctively, but do it deliberately. Like, you first make a quick check whether yelling would be appropriate in the situation, and if you decide yes, yell at them.
Interesting, I read this post as corrective advice to a typical rationalist failure mode, which is to spend a lot of time thinking about feelings and what the "right" way to respond to them is instead of just letting them be and then doing the extremely obvious thing.
The thing about many of the feelings you list here is that their main effect on me is to make me feel bad, instead of to alter my cognition. As an example: muscle fatigue, cold/heat, and itchiness mostly don't lead me to have false beliefs (except that tiredness will affect my thinking), and mostly serve to make my experience unpleasant (aside from itching, which also makes me start itching unless I actively try to stop).
I cannot think of times that I was outside and thought "I need to go inside soon, this is damagingly cold!" or was physically exerting myself and thought "I need to slow down or stop unless I'm okay with being sore later". These seem like pretty weird thoughts - it seems hard to predict whether I'd be sore due to the lack of direct feedback (I can be sore without tiredness, or not sore even after strenous exertion - because it's more about total usage over an extended period of time, I think), and wouldn't affect my decisions due to how small a harm it is.
What do you mean by "removing the negative valence associated with [minor injury]"?? The negative valence is that it hurts!
One of the things I love about parenting is being frequently reminded how many things are not the default for most people. While I see this most clearly in my 11-year-olds, I also see it in other adults as well as in myself. One of these human defaults that I think is worth improving upon is the instinct to “trust” your feelings, i.e. act on them without much consideration of:
What is the Source of My Feeling?
We are often wrong about the source of our feelings, whether because we’re hangry, sleep-deprived, stressed, or in any other altered state that changes our typical reactions. When you’re very hungry, someone doing something relatively innocuous can result in you getting angry at them. The biggest contributor to your anger is not actually the actions you’re responding to (since under normal circumstances you wouldn’t react with anger) - it’s the fact that you’re hungry.
Other times we might be right about the general source, but getting specific is necessary to productively act on the feeling:
How Should I React to My Feeling?
Even when you correctly understand the source of your feeling, your gut reactions are often not actually helpful in addressing the issue at hand or accomplishing your goals! Similar to the maxim in design and creative disciplines of “Listen to the problem, not the solution”, with feelings it seems you should acknowledge your feelings, but don’t blindly do what they seem to tell you to do. Consider the following situations:
One of your kids hits the other, and you yell at them to stop:
You’re attempting to do a standing back flip, but after jumping you get scared and open up all your limbs, flailing wildly:
This one from my kids: you’re having trouble falling asleep, so you open your eyes and look at the clock, or get out of bed to talk to a parent about the fact that you’re having trouble falling asleep:
Applications to Physical as Well as Emotional Feelings
This concept can also extend to the realm of feelings in the sense of physical sensations, not just emotions. Here the source is unlikely to be misidentified, but the best reaction to the feeling is often not the instinctive one:
Choosing Your Actions is Beneficial
So at a high level, my point is this:
This all falls under the general concept of intentionally choosing how you act (or choosing to not choose and just go on instinct if that’s better for a certain situation!). Based on the number of times my kids respond to “Why did you just do that?!?!” with “…I dunno.”, it seems like choosing your actions is not the default human condition, but it is a default that can be changed with practice. Ultimately, by learning to view these internal signals not as commands, but as data, you can take back the steering wheel and consciously decide how to respond.