Because i think in all my play i've seen 1 trip done.. A trip that probably wouldn't have been done if the user wasn't able to use his Unarmed skill.. I've never even seen anyone ever try to take "close combat: trip" or something like that. I didn't even know this rule for the longest time because it always made perfect sense that when doing a manuever, you use the attack roll of whatever you're doing the manever with..
Also just the way I think of "Unarmed combat".. I think of it as a skilled martial artist, which involves doing cool manuevers like sweeping, a common martial arts move (I guess if the martial artist was a boxer, I might have a different POV).. Grab I could definitely see being different tho..
When Wolverine attacks someone, punching and kicking vs wielding his claws seems to be very different to me. The claws are bigger, they weigh more, there are special considerations to be made so you don't cut your own leg off.. Even sabretooth style claws are signficantly different in how you attack with them compared to punching and kicking.. When you're sweeping someone, you're still doing an unarmed attack, just at their legs.. Or if you're trying to kick a gun out of their hand, you're still kicking them, just aiming at their gun hand rather than their head, body or whatever..
Close Combat Manuevers just didn't ring through with me because then you'd get it and suddenly be good with everything as long as you're doing a manuever.. Like I'm awesome with swords, staffs, unarmed, and daggers... but only when disarming, I suck with them otherwise (extreme example)..
I see your point of view and everything, just doesn't ring right with me.. I guess my take on trip is sort of a "houserule" based on my experiences in my games (trips being very rare) and personal perspective.
I personally don't really have a problem with the claws or whatever falling under Close Combat Unarmed. Like you said, he's probably just going to use it for the better attack, I just don't think it works by a strict interpretation of the rules as written (neither does my trip stuff, but that's kind of moot to the original topic).. I could be wrong.. After all the shapeshifter archetype in the book has many ranks in the close combat unarmed skill and he'd obviously use claws. Catwoman also looks like her claws fall under unarmed.. So probably the way you're saying