I don't think that monthly expansions are a bad thing, as long as the fans like it. Look at Team Fortress 2. http://www.teamfortress.com/history.php It has received free expansions since 2008 and it still has a large active community.
The industry doesn't change, it learns. An example of this is Super Mario. New Super Mario Bros. U was released in 2012, with the same basic gameplay left mostly unchanged since 1985, and still sells. The difference between creating games or dlc from when they first became popular is that we now have experience of what does and doesn't work for each situation. Mobile games work well with microtransactions, while big AAA games do not work as well.
I think RCTW would benefit greatly from seasonal to annual expansions. I'd prefer higher quality expansions that take longer to make to cheap expansions released frequently.