Wouldn’t it be more fun and flexible if the 4-3-2-1 formation allowed the central CM to be changed into a CDM?
This would let players use a 4-1-2-2-1 shape with 1 CDM, 2 CMs, similar to a 41212 narrow but with one ST and 2 CAMS. It would improve defensive balance and make the formation more enjoyable to use, especially for players who like a mix of attacking play and stability.
Right now, many players already try to use the middle CM as a holding or deep lying playmaker midfielder and leaves a few gaps, so adding this option would make the system feel more natural and realistic.