Yes, I know these arguments, but they don't hold water (well, they are correct, but don't justify anything).  They at best answer the argument "why did Satoshi didn't use RIPEMD-160 alone".  The question is why didn't he stick to just SHA-256, and kept a 256 bit address.  And if he really wanted to decrease the number of bits from 256 to 160 (but why on earth ? - to save space ?  then why waste a lot of space in the signature + key ?), he could simply keep the first 160 bits of the hash.  

Let's go through a few arguments that are given there.
1) the "interaction between ECDS and hash function".  That's totally ridiculous, because given that the secret key is a random number, the public key is a random number too (there's a bijection between both, it is a cyclic group).  So there's no "interaction" between a random number, and the hash function.  But if ever there was a "funny interaction" between ECDS and the first hash function (which makes no sense as I just outlined: it's a random number), say, that it always gives one of the 10 same hashes, then applying a second hash function is not going to solve it, on the contrary.  Talking about interactions, by cascading things, you can only *increase* the chance of an undesirable interaction.

2) the "double hashing to avoid the extension attack" in this case is also weird, as the original key is only 512 bits (in long format) and hence, there's no need for the application of Merkle-Damgard, as one single block hash primitive has to be called, and there's no "extension" possible.  In other words, this is a protection against a kind of attack that is totally irrelevant in this case.