This is the correct way to maintain and develop a game, especially a live service game. The idea of abandoning it because it only had 'moderate' success up till now always baffles me.
Keep refining, polishing, adding more content. Basically build it up, like everything else that actually has real value. In the present age, if you don't have instant 'mega' hit in pretty much anything, it's automatically considered a 'failure'.
This extends well beyond video games, and it unfortunately destroys the habit of nurturing and growing things from small and moderate beginnings to greatness. These days, if people don't achieve instant greatness in an endeavor, they immediately jump ship and move to the next new and shiny thing, hoping for an instant hit. Instead of digging deep where they are and slowly growing, it's always off to the next thing. In this way, they unknowingly never learn what it really takes to achieve greatness. /End of rant/.
Anyway, this is the correct approach to development imho. Kudos to the 343 dev team for building this out. Better late than never.