Not So Deep Tautologies

Hanno and I have written a couple of articles on how tautologies, sentences like "It's raining or it's not," can be used in conversation meaningfully. Since a tautology is always true, yes it is either raining or it isn't, it tells you nothing about weather, it is vacuous. But we use them all the time in ways in which they are not meaningless, for example, "Boys will be boys," "First thing first," or A: "Do you want this old machine or a brand new super fast one?" B: "For me, a computer is a computer." We took one category of what we termed "deep tautologies" and worked out the way conversational context gives the tautological utterance meaning. The key to the listener unraveling the speaker's intended meaning was that it was that it was obviously a tautology, obviously a sentence that has no meaning of its own and therefore, as the great philosopher of language H. P. Grice pointed out, it was a violation of the basic principles of conversational cooperation and thus a signal to the listener that the meaning requires an inference, what he called an implicature in order to understand why someone cooperating in the conversation would say something that appears unhelpful or meaningless.

But recently I've become fascinated by a group of expressions that are hidden tautologies, sentences that say nothing, but appear be actual meaningful contributions and I am wondering why we use them. Consider this exchange that I've heard more than once:

Waiter: "How spicy do you want it?"
Diner: "I don't like it too spicy."

or

Hairstylist: "How much should I take off?"
Customer": "I don't want it too short."

In both cases, the response seems meaningful, but it isn't. What does "too spicy" mean? It means "spicier than I like it." So, what the person really said is, "I don't like what I don't like," and has given the waiter absolutely no guidance in the level of spiciness desired.

I suppose it might be intended to rule out the extreme, but even here it gives no indication where the extreme is located which was the information requested by the asker.

Yet, you hear these disguised tautologies frequently. Why the linguistic evasiveness? Do they mean something that I'm just not picking up on and if so, what? Where deep tautologies are contributions to the conversation that are shaped like sentences that don't make a contribution, these seem like contributions, but really aren't. Is it a psychological/social thing where we don't want to seem unadventurous, so we hedge? Or is there an actual meaning that I'm missing here?