It's as close to a price tag as there is. As the AR goes up the number of usable cards goes down - that sure sounds like a price to me. In your example, they are more reliable BECAUSE they are 'cheaper' to animate. As Misaki is a sidekick I kind of get it now - she can't one shot a puppet (Alice), or do a powerful ranged attack (Judge), or blip on and off the board (Bete), etc.. My only gripe is Misaki's higher than average defense - it doesn't seem thematically appropriate being that she's all about speed and maneuverability.