I tend to agree to this observation. For example, I believe (but I don’t know of any data that can comfirm it) that the British will say “Half past seven” more than Americans will (I think they’ll tend to say “seven-thirty.”)
I’m curious: Do your textbooks tell you that after the half-hour, one can say “eighteen to four” in two other ways? (“Eighteen of four,” and “eighteen before four.”) And also, which particular textbooks are you referring to?
Speaking of AFfect (as opposed to efFECT), I totally agree with you here, and there’s a great article about this (-Ochs, E. & Schieffelin B. [1989]. Language Has a Heart). Sorry, I don’t remember what text it’s in.
Anyway, the point of “Language Has a Heart” is that affect is built into the grammar of all languages (syntax, morphology, etc.) For example, you can say:
a) He always comments on my appearance. [neutral or positive]
or
b) He’s always commenting on my appearance. [negative, it bothers me]
By shifting the aspect (from simple to progressive), you convey a mood.
Or, In Spanish, you can refer to:
a) mi carro (my automobile)
or
b) mi carrucho (my junker)
With morphology, you can express how you feel about your car–your mood.
But I don’t think time expressions are used to do this. I don’t think the difference between:
a. three forty-two
and
b. eighteen to four
is about mood. I think it’s just more a question about ideolect.
Could it be that your textbooks are drawing upon British English, and you find this different in tendencies you see in American media?