Difference between 書かないようになった and 書かなくなった?

Question

Example sentences: ぜんぜん長い手紙を書かないようになった。 ぜんぜん長い手紙を書かなくなった。 My Translation: I never write long letters anymore. I believe they both mean the same thing but there's obviously some difference I don't know about.

Answer 1

The first one would be over a longer period of time with a gradual progression. Perhaps the speaker is older and can no longer write as long as they used to. This form (ようになる) is often used when describing things like acquiring/losing skills, changes in population/demographics and more.

The second one is a sudden change.