Each decade can be identified by its iconography, and this is usually a reflection of the soul of that generation, the seventies were in the world of modeling, a great era, boxart was going through its best time, before the Laws on it, to me. The best opinion was that of Revell, but in reality there were very good painters in various brands.
Art could very well enhance emotions, unlike current decorative art, there could be explosions, combats, all those things associated with great emotional energy, that gave that Boxart a strength that others do not have.
A few samples
