@MarzZee
There is a point in the game you clearly missed. There is an orange button in the corner that, when clicked, gives you a menu that lets you buy more boards to work on to rake in cash. There are upgrades that let you rake more cash in from a single board, and sometimes the games are fun... for time-killers. Just in case it didn't dawn upon you, there is more to the game than hitting a goat up in the air.
I played Bloons Super Monkey 2 on Ninja Kiwi website, and on level 1-5, there was a boss. When I played level 1-5 here on Kongregate, there wasn't a boss at the end. What happened? By the way, great game.
I think the reason why a lot of people liked the first game is because there isn't a complicated health system for the enemies. That's also maybe why people stuck with this series. Just my thoughts.