In my opinion there are two reasons why Canada increased IELTS listening points

1. IELTS listening is easier than other modules and give more points to the majority of the candidates.

2. Listening of English is the most important after your landing in Canada. Because you cannot converse with natives if you are unable to recognize what they speak.

So focus on IELTS listening test if you want to get 4 points in listening area of IELTS.