--no-install means that all dependencies will be calculated and
composer.lock will be generated. If you can't update (because extension does not allow beta 15),
composer update --no-install will fail in the same as
composer install - nothing will be saved or installed. It does not make anything safer o simpler, since
composer update --no-install && composer install works the same as
composer update. As long as you don't want to skip installing new dependencies or want to investigate
composer.lock before installing them, it makes no sense to use
--no-install, it only makes everything more complicated, especially for Composer 1.x users.