The baseball card wars had been raging for the past three seasons and in 1955 Bowman showed it still had some fight left. They upped the number of cards in the set by nearly 100, up to 320 cards. That made it their biggest set since 1951.
And as for design, they were going all modern on us. Color TV was in its infancy in 1955. It would set you back over $1,000 for a color TV and very few programs were even broadcast in color. But a color TV is what Bowman featured on their cards. They were hip and cutting edge.
The bigger set means more Cubs. There were seventeen Cubs, including the only Bowman card of Ernie Banks.