It will be really helpful to increase the health of CNC as it dies very quickly
(Ex: run over a mine - 80% health is gone, take fire from metal rain for just 3-4 seconds its dead). Even on upgrading it, very less health is added.
Training it also takes a lot of time (That's fine if the unit is worth waiting for like titan tanks)
I see players using it rarely during battles. Maybe because of the above reasons.
Its a really awesome unit for boosting troops and offence.