Hussein Hassan posted:
A. Objective/emotional adjectives
B. Subjective/rational adjectives
I think you've mixed them up. I'd say:
A. objective/rational adjectives
B. subjective/emotional adjectives
Group A adjectives are more formal, while group B adjectives are more informal and thus allow for this pattern you mentioned in your initial post:
'it' can be used as a preparatory subject or object for an -ing form, especially in informal style. We often use it with adjectives.
I don't think you will find a definition of group A and group B adjectives in a book, but I'm sure you can see the difference between:
A. It was important to see her. (NOT seeing her)
B. It was nice to see/seeing her.
While "important" defines or describes what it was like to see her, "nice" expresses what the speaker feels (or felt) after (or when) seeing her.