Because you think your bitcoin private keys are safe ?
Because public transparency is what supports their value, not time-bombed
clumsy layers of obfuscation.
I knew your non-sequitur arguments were going to end up here
Your argument against "time bombed obfuscation" is exactly the same as the argument that tells people not to encrypt anything, that way it will not be cracked one day. Use http, not https, because it might get cracked. Don't use encrypted passwords, they will get cracked. But in the same vein, don't use digital signatures, they will be cracked too. And then, you cannot use it to prove your ownership of coins, because others can do that too.
In other words, your arguments against using cryptography, because one day it may get cracked, are valid for ALL cryptography, including using encrypted communication, encrypted data, and, of course, crypto currencies, including bitcoin.
So the argument that cryptography shouldn't be used, because it is not safe (a bug, a powerful attacker, advances in crypto analysis, an error of principle....) also invalidates the value of bitcoin. If you think that, say, 6 years from now, all bitcoin addresses can be cracked and their digital signatures obtained, then bitcoin should not be used as its monetary belief is based upon the digital signatures being safe. If you think that just any sophisticated hacker can get into just any computer to steal secret keys, then bitcoin will not be usable either. So the argument that cryptography will be cracked and should not be used, is an argument that makes bitcoin worthless too, and you shouldn't any form of crypto currency.
With that problem resolved, we accept that cryptography works (or we get out of crypto currencies). The chance of the cryptography of ring signatures being broken, is of the same order as the chance of digital signatures being broken: it is more or less similar cryptography. So if one can deanonymize the ring signatures, that comes down being able to deduce digital signatures if one knows bitcoin addresses too. If bugs can happen, they can happen in any piece of code, so in bitcoin's code too.
Once we accept that ring signatures are just as safe as bitcoin signatures, there's nothing that makes that transparent block chains are more "certain" than digitally ring-signed block chains. In both cases, you accept that the signature proves cryptographically the correctness of the underlying claim. In the case of a bitcoin signature, you accept that the signature was produced by *the* owner of the unspent transaction output address secret key. In the case of a ring signature, you accept that the signature was produced by an owner of an unspent transaction output address. The ring signature cannot be produced correctly if the unspend transaction output was, in fact, spend (the rest of the block chain would signal that), in exactly the same way as you verify explicitly in the bitcoin block chain that this unspent output was, well, unspent. The ring signature doesn't work if it was spent. So you know it wasn't spent. The only thing you don't know is WHICH ONE it was. But that shouldn't matter. The only thing you need to know is that AN unspent output was used, and that this very signature is going to signal now that this output is not going to be able to make another ring signature. Exactly as with bitcoin.
Now, if you think that the cryptography is not working, then you shouldn't believe either, that the digital signatures of bitcoin work. Why would you believe digital signatures of bitcoin, and not ring signatures of monero ? And the cryptography is such, if you accept it, that only one single previous unspent output can produce the right ring signature, and by doing so, will signal that this output cannot be re-used for another ring signature. That's all that is needed. It is because Satoshi didn't know enough cryptography that he showed the explicit outputs and inputs. But the only thing that he needed, was the proof that an output was spent only once. Ring signatures prove this in the same way that digital signatures prove ownership of the secret key.
So, in summary:
- if you start from the idea that cryptography cannot be correctly implemented, will always contain essential bugs, and/or will always end up being cracked, then you shouldn't, ever, use cryptography, not for monero, nor for bitcoin, nor for https nor for passwords.
- if you start from the idea that no electronic device will ever be safe, then: same conclusions.
If you think that one can use bitcoin's code, cryptography, and secret keys, then there's no reason not to accept the cryptographic proofs of no double spend by ring signatures or the proofs of possession by secret key by ring signatures. That's the only thing a block chain is used for: proving the absence of double spends and prove the right to spend using digital signatures with secret keys.
In other words, in as much as you accept cryptography, the monetary functions of cryptography on the monero block chain are the same as those on the bitcoin block chain (proving "right to spend" and proving no double spend). And in as much as you think that cryptography is a failure, then you shouldn't use nor monero, nor bitcoin.