Passing each column should count for 10 points, and your score should be dinged -1 point for each keypress. Pressing a key that's not on the screen should be a -5 point penalty. Game over if you drop below 0 points. That would solve the button mashing easy win problem.
Also, perhaps my skills are lacking, but the game essentially becomes impossible after the columns become 6 blocks wide — the fraction of open (i.e. fully breakable) rows becomes small enough that open rows between adjacent columns are often further apart vertically than the ship can travel, given its speed and the game's horizontal scroll rate. I like the sibling commenter's suggestion of pseudorandomly carving navigable paths between columns, as opposed to the current method of having a uniform 80% probability that an individual tile is breakable.
Yep, you can just spam press the keyboard