CUSTOMIZATION MECHANIC - DIARY

I have an idea for a fun, RP-centric character customization mechanic -- the Diary.
The basic concept is that at certain intervals, the main character/PC would write in their diary and respond to recent plot events. These responses would be player-controlled, and so would make intimate the experience of the plot.

Each plot event the character could respond to would be represented by a "keyword." When writing a diary entry, the player would choose a keyword from the word bank he or she had accumulated so far, and then choose a primary emotional response. (Note: emphasis on primary.)

For the more involved role-players, the player would also be able to type sentences containing a single keyword and then type responses containing a single emotional response word. (For example, you could type a whole paragraph denoting your feelings as the main character. As long as, per each keyword, there came an emotional response word before any other keywords, everything would check out fine.)

The data collected by these diary entries has any number of obvious consequences: you can use it to determine class customization, as a platform of abstraction for choices (that is, you can potentially make the plot change based on solely these reactions), anything you set your mind to.

Without regards to feasibility, does this seem like reasonable design to anyone?
And then with regards to feasibility, does this seem viable? It seems like if we could figure out how to make this, we could make it modular/pluggable enough that it could just be a shared script and people could import this functionality and use it at their leisure.

What do you guys think?