Why does "too [adjective] a [noun]" require the determiner to come *after* the adjective?

Example: John is too good a person to do something like that.

If you can say John is "a very good person to do something like that", then why not "a too good person to do something like that?"

Why does "too good" have to come before the determiner in this kind of construction? And parenthetically, is there a term for this particular syntax?

Why does "too good" have to come before the determiner in this kind of construction? And parenthetically, is there a term for this particular syntax?

I can't really answer the 'why' question, because it's simply the way English works. Somehow, English has this construction, and grammarians use the term 'predeterminer' or 'predeterminer modifier' to describe such adjectival phrases as 'too good' in your example, apparently because they come before determiners (the indefinite article a).

Of course, there are many different types of predeterminers as well, as in:

John is such a good person.

But the kinds of adjectival phrases in question are limited to adjectival phrases having the construction starting with a small number of degree modifiers such as: too, as, so, how, this, that, etc. As long as adjectival phrases start with one of these degree modifiers and are followed by a, they can be predeterminers.

John is as good a person as Jane.

John is so good a person that he can't do something like that.

John is as good a person as Jane.

How good a person is John?

John is this good a person.

John is that good a person.

Since they're predeterminers, you need the indefinite article a. Hence, you can't predetermine a plural noun or a non-count noun.

*They're too good people to do something like that.

*This is as good coffee as that.