I think the mech makes perfect sense for the Clans. It's a mech you choose in desperation. Let's say you're an older warrior (late 30s) and you haven't really done much of note. You want a chance for your genes to live on, maybe get a Bloodname. But that's not really gonna happen for just regular old Mechwarrior Steve. So you are going to put all your eggs in one basket.
From the perspective of your Clan, you're nearly washed up at this point. But they know that you're getting more aggressive, more desperate. You're going to start taking needless risks anyway, no matter what they do. That's just what Clan warriors do when they reach a certain age. So you might as well give them a mech that suits them.
In a way it would be a mark of shame to get assigned a Hunchback IIC, because it means your commanding officer thinks you're over the hill and all washed up. It's the equivalent of a modern single woman getting a bunch of cats. "Well, she's given up on life..." On the other hand, if you're honest with yourself about how your career has gone, you know that this is your chance for glory. With some decent to-hit rolls and damage grouping, you could pretty easily wipe out most of an Inner Sphere lance, or even a Clan star, before you ran out of ammo. I just ran a couple of Megamek games with one Hunchback IIC vs a 3025 IS lance (a Valkyrie, a Thunderbolt, a Vindicator, and a Shadow Hawk). The BV was heavily in favor of the Spheroids. In the first two games, the IS mechs ripped the Clan one to pieces before he could do much (he can't get much of a movement bonus). In the third game, the Clan mech won initiative a couple times, fired in ultra mode, and killed 3 of the 4 mechs, and crippled the last one before he finally lost a leg and I exited the game.
From the Inner Sphere perspective, these mechs would be very useful. No, it's not the Clan mech you'd pick if you had your choice. But if you can get it in the right position, it's like turning loose a rabid pit bull. No mech out there is going to feel safe if they look over and see a H-back IIC moving into medium range. I think you'd try to use it from ambush, and in areas with really bad visibility. It's job would be to massacre one or two enemy heavy hitters, and then retreat to resupply.
