I just played a 1v1 on Fear (terrible map, needs to go) as Space Marines versus Tau. My opponent opened the game up by trying to Vespid rush me, which failed as I had built a turret after my Chapel Barracks. Having two SM tac squads, I tried to take advantage of the failed rush by going to his base immediately while a scout squad capped points. When my two squads got there, they were almost fully reinforced, and encountered a single kroot squad of 6. One tac squad assaulted while the other shot from closeby. I noticed that my tac squad in combat was taking far more morale damage than the Kroot squad, going to 150 morale from 300 in only a few seconds of combat despite having double the troop strength of the Kroot. The Kroot retreated outside the base, allowing me to assault the Kroot Barracks.
Very soon after, two Kroot squads came back at nearly full strength and attacked my two full tac squads. This time, the Kroot were almost immune to morale damage, not moving from their max of 300, while one of my tac squads broke in ~10 seconds and another one was down to 50 morale. I was forced to dance the two squads around the Kroot, until a third fully reinforced tac squad came. One of the two Kroot squads never moved from 300 for a second, and the other was losing morale far slower than my fresh tac squad which was promptly broken from fighting an inferior force. A third Kroot squad came out of the Barracks. With so many casualties from not being able to damage his initially smaller Kroot force faster than he could reinforce it, I had to retreat, losing two whole squads in the process.
I built a second tac squad, and got two flamethrowers for each of them to try to break the Kroots' morale before they could break mine. However, he had researched Feral Leap which completely circumvented the flamethrower's range and therefore the morale damage. At this point, I had used up so much requisition on filling expensive Tactical forces to fight Kroot Carnivores that I had lost both the rush to tier 2 and map control. The game was pretty much lost. I tried to build a Machine Cult to quickly get out Landspeeders and Dreadnaughts, but they were just torn apart by invisible stealth team spam.
Something is very wrong when a relatively cheap unit intended to be an auxillary for tying up enemies so that Firewarriors may kill them from afar, is able to stand toe-to-toe with a more expensive and more plentiful melee-oriented core army unit and win. This is not just true of Space Marine tac squads, but also of Chaos tac squads, Ork Slugga Boyz, and Eldar Banshees
I don't know if Kroot damage is too much or not, but the morale damage really needs to be dropped.