The split RAM pool, the overall amount of RAM, the late implementation of the more advanced streaming engines, the slow improvement of OS RAM usage
Of these, I agree with the last one, but I don't feel the others quite so much. They are trade-offs that primarily influence 'ease of development', particularly for multi-platform development, and even more particularly, porting. While I do agree that the reality is that being friendly to developers and friendly to multi-platform development and ports has become more important (this is something that Sony grossly underestimated, and that they feel the pain is borne out strongly by their sea-change for the NGP), the overall amount of RAM is not different, the split RAM pool has bandwidth benefits in various areas, and the implementation of more advanced streaming engines wasn't so much late, as just not implemented because of cross-platform reasons more than anything else (though here too, Microsoft was smarter in providing an easy SDK solution that automatically used implicit streaming/caching to HDD).
I am slighly suspicious however that the way Sony has implemented its harddrive encryption has crippled its harddrive speed somewhat more than would have been desireable, though I haven't heard anyone about this in particular, and I don't know if anyone has done comparative speed-tests of the same harddrive in the PS3 and in the PC.
There's an asymmetry in the link bandwidth between RSX and Cell that I am curious about, as I've not seen an explanation as to why.
Which one are you referring to? Because this has been discussed quite extensively. There are only two standout asymmetrical parts, the 4GB from Cell straight to framebuffer (typically used by the BluRay player type software), and the 16MB connection for Cell initiated reading from GDDR.
Then there is the reality of increasing costs and the demand for parity in multiplatform development. Any outsize advantages on a given platform tends to be whittled down.
Fully agree with this one, as also mentioned partly above.
Then there's the age. Technology has moved on from the point the consoles were set in stone.
There are latency numbers for the PC in the DICE presentation for certain operations that are orders of magnitude lower than either console at default.
Correct, but latency needn't be that important either, as long as it is low enough - throughput matters more. In the rest of your story, you seem to be glossing relatively easily over the various very big issues DICE had with DirectX11, that they have contacted and tried to solve with Microsoft?
As for SPE backward compatibility, software emulation may be easier than expected, because each SPE is a fairly independent unit with a limited set of features and very predictable behaviour. It may end up being quite less of a challenge than EDRAM posed for PS2/PS3 backward compatibility.