Sure it's slow, but whatever.
Blizzard looked at making Overwatch F2P, with rotating heroes, but that didn't work cause you need to have access to the full roster.
So now they sold us access to all heroes and future updates for 40/60 bucks, plus put in some tiny insignificant shop system that doesn't impact gameplay so that they have revenue for a long time and are able to release content.
Alternative would be paid DLC packs that split the community.
So unless you are a mega splerg and have serious issues that you need help for you really shouldn't care.