Here, it's not really a simple case of the words swapping position. In fact the equivalent phrase for use with a noun is not "too much", but "much too much/many": "it is much too painful to walk" ~ "I am in much too much pain to walk". The adverb "too" cannot be used by itself to qualify a noun as it can with an adjective (though you can say "too important", you can't say, for example, "too books", "too butter"); instead, to express an excessive quantity, you must insert "much" or "many" before the noun (depending on whether the noun is uncountable or countable): "too many books", "too much butter". Whether you're using an adjective or a noun, a "much" can be added before the "too" to to indicate a more extreme excess: "much too important", "much too much butter", "much too many books" (though with countable nouns it's much more common to say "far too many").

It is much too important to forget. It is much too expensive to buy unseen. It is much too late to apologize. He is much too fat to fit in this seat. He is much too inexperienced to be given this position/job. He is much too irresponsible for you to rely on.

Thank you, Brent for some useful examples!

Hey there, TOO MUCH + NOUN has a negative idea of the quantity. EXAMPLE: 1) too much money ( I can not buy it). 2) too much time ( I don't have time to do it) MUCH TOO + ADJECTİVE makes the adjective more intense. ( like saying very) EXAMPLE 1) much too painful ( It is very pain! ) 2) much too boring ( It is very boring! ) Why is like this? Well, it is important know the rule and how to use. It is little less important to know why. After you learn a grammar rule and use it, the why is not so important because you are using English to communicate! Too much + noum is one of my fav. rules to teach! Students sometimes confuse TOO MUCH with A LOT or ALOT OF. The two ARE NOT same. LET'S TALK! https://www.italki.com/teacher/4328144