Yeah, I for one appreciate the fact you were willing to give the game a legitimate shot.
But it's important to put things in context.
Galaxy 2 also had two or three green stars per level. But every time you grabbed one, they made you restart the whole level, make you retrace your steps, then keep going just a bit past where you were to grab the second star... and then have to restart the level again, doing the same thing. In total, there were 120 yellow stars and 120 green stars, for a total of 240 game goals.
In 3D World, there are somewhere around 90 goal posts, 80 stamps, and roughly 350 green stars, for a total of about 510 or so game goals/collectibles. 3D World has more than twice the number from Galaxy 2. The only difference is they don't make you continually restart the level after you find each collectable, so the game is MUCH more streamlined and respects your time more. And even after trimming all the fat and fluff that padded time in Galaxy 2, 3D World STILL ends up being about the same amount of play time. There's just that much more content.
So don't be disheartened. You've still got a lot of game in front of you.