Thank you for playing!
You're correct in that the game does incrementally increases in difficulty as you gather more stars, with longer and faster combinations.
And I agree with how repetitious it is... Even I myself can only play it until it very swiftly derives me of all my patience, haha! (:
Perhaps it might work best as a dime-a-dozen hyper-casual time-waster you'd boot up on your phone once in a while (à la Flappy Bird, for example), maybe as a memory+processing exercise. But I imagine a large appeal of those kinds of games are still the customization options unlocked through achieving certain gameplay milestones, etc..
In any case, thank you again for playing and providing your thoughts!