I should think one of the big reasons that players over-value ramps in terms of raw cost is down to game flow. As soon as you put a ramp in there, the whole style, structure and dynamic of a game instantly changes around it. It's not impossible to create decent flow without a ramp, but it does become considerably more difficult. This game seems to have pulled it off quite well, it doesn't look too bare, and I love how the in-lines are used as ball locks.