Wordpress goes with react, drupal picks angular2, and laravel favors vuejs.

This is no surprise, wordpress is extremely popular these days for all users, a huge angular2 client framework might be an overkill for many of its users. Drupal on the other hand is doing the more complicated websites, and its "ordinary" user base is shrinking, so angular2 might attract enterprise users.

Laravel is arguably the most popular PHP framework today, choosing vuejs as its client framework gave vuejs a strong boost for sure.