Its not like you want to use stock grenadiers, by the time other elites hit the field. Not to mention that its pointless to use them without G43.
On top of that, grenadiers kars don't have exceptionally good close range damage, and the whole DPS of jaegers comes from sniping models.
Point being, if you want to counter jaegers just close the distance which wont allow them to get easy snipes.
if only they had options to defend these jaegers (sturmpios/volksgren STGs) from close range specialized squads