Well, let's see...
1) first and foremost, reversible transactions open up a wonderful new world of petty fraud, especially for companies selling digital, ephemeral products (such as ebooks, or software, or online services) because delivery of those is problematic to prove outside some pretty in-depth interpol investigation.
Right. And with Bitcoin if someone steals my wallet and spends all the coins in it I'm screwed. No recourse. All my money is gone. With Credit cards I'm not liable and all my money is still there.
So you are willing to shift the responsibility for your carelessness on other agents in the market who had nothing to do with your poor security decisions and terrible luck ?
:-P
Bitcoin shifts damage exclusively to the consumer. I have no economics background, but aren't there more consumers then merchants? Aren't merchants themselves consumers? PayPal is not a perfect system. Bitcoin does not offer improvements to the consumer- just to the seller.
Well, it seems to me that it's not a question of "who has more numbers" but a question of incentives such a set-up creates.
Shifting all the damages to merchants penalizes fair merchants and mildly annoys (at best) scammers
Shifting all the damages to the consumer does penalize a careless / inexperienced consumer, but in the end a consumer has more ways to do due diligence on a merchant than a merchant on a consumer (online merchants are, by necessity, somewhat static, while online consumers typically are pretty ephemeral)
To me, chargebacks are obviously a corrupt system that creates perverse incentives
Also, nothing in principle prohibits various "fraud insurance" schemes (including ones I would consider "perverse"

) from arising, but, due to bitcoin's transparency (
paradoxically, bitcoin is perhaps by far the most transparent online payment system, since everyone can view everyone's transaction log)
BTW, transparency is one more notable feature of bitcoin - you can go and take a look how your transaction is "moving around" in Block Explorer, which might have a lot of uses.
Also, Googled and looked into bitcoin-police. It looks very new- two posts on a blog, wiki with a lot of info on the mybitcoin scandal. Have they successfully helped anyone recover funds? Or at least, brought any bitcoin scammers to some form of justice?
Everything about bitcoin is by necessity young.
Also, bear in ming that new functionality is being developed and tested (check out multicoin, it's amazing)