I never actually thought I'd have to post on this forum, but the sheer astonishing lack of basic reading comprehension displayed in this thread has driven me to it. (No, that isn't an accomplishment.) Similarly, I'm not going to bother quoting particular posts to reply to them, because, quite frankly, reading them the first time was painful enough.
Firstly: I often play Suicidal with Jabau. I know how he plays. To everyone saying he mostly uses guns: No, you are wrong, and should stop pulling things out of your arses. He uses the Katana for everything except Flesh Pounds, and to good effect at that. Crawlers? Yes - if you move backwards at the right time, you can dodge their leap and slash them in the face without taking damage. It can be awkward if there's a group of them, but it's still doable. Sirens? Again, yes - if you time it just right, you can bum rush them without taking much damage, or if that doesn't work, you can try to ambush them (since the scream attack uses simple point-to-point line of sight for hit detection, which can be blocked by just about anything). Groups of Sirens take a bit of creativity without backup from the team, unless you defer to your ranged weapons; probably the best way to deal with them is to split them up either by luring them around obstacles (or off ledges) or by throwing a grenade at them from far enough away. And I don't even know why people whinge about Husks, because dodging their fireballs isn't that hard, and one strike to the head will knock it off. The Crossbow is exclusively for the Flesh Pounds, though it isn't quite as effective at that as it is in the hands of a Sharpshooter (I'm pretty sure it takes an extra shot in 6-man Suicidal; maybe two).
Also, while I'm at it: He's well aware of the Chainsaw nerf, as he's said in this thread. If you think he isn't, you haven't read his posts properly, and thus should not be commenting on them.
Moving on to the topic at hand: No one is saying that the Flesh Pound melee decap was difficult in isolation. With a bit of practice, it could be executed reliably in almost any circumstances, and if the circumstances didn't permit it, a smart player could generally manipulate them easily enough (e.g. moving to better terrain). What made it particularly dangerous (besides the damage inflicted by a punch to the face, which was never pleasant in Suicidal especially, and a good way to lose armour) - and require teamwork at that (shock!) - was the fact that the person doing it was prone to attack from the other specimens. Everyone saying that its advocates don't like teamwork apparently forget that on Suicidal, Gorefasts hurt. A lot. So does the Siren hiding behind the Flesh Pound, and in the later waves especially, there almost always is one (at least). The team was therefore needed to protect the headhunter from the hordes that wanted to shred his sides. They also had to be on the ball in case something went wrong (e.g. the team misjudged the Flesh Pound's target, so instead of facing the valiant attacker, the FP brushed him off, then took the hit in his side and expressed an objection).
Note how I never said "the Berserker" in the previous paragraph. That's because, as Jabau has pointed out, any perk could do it; it was usually left to the Berserker simply because he was much better at it than the others, and was less affected by the Flesh Pound's attacks (and those of his company) than his closest competitor (the Commando, who, in my experience at least, was an uncommon sight in Suicidal prepatch anyway). Jabau's point - and I agree with it - is that the ability of any perk to take a Flesh Pound's head (though not without cost) stopped Suicidal from being a Sharpshooter fest like it is now. They were still common, but not absolutely necessary.
But what weapon should the other perks use? I agree that the knife and 9mm taking it off in one go is a bit silly for gameplay reasons. But what if it wasn't one go? What if weaker weapons required several hits, a Fire Axe and Katana an alt fire swing, and the Chainsaw a full second of cutting? That's just my idea, but there we go; the particulars can be addressed one step at a time.
I think that just about covers it.