Yes, that would explain why they make all the chips the same, because 1 fab is cheaper than 2. But why disable the L2 cache? That just makes the chips perform slower. They are going to cost the same for them to manufacture either way, the only difference is that they disable 2mb of cache. That's more trouble than just leaving it and setting the multipler and clock, which they have to do anyway.
well it wouldn't make sense if Intel didn't make some differentiations. they need lower models that perform less so they can sell them cheaper. they wouldn't be able to sell higher models if the lower models weren't crippled, seeing as low end models are cheaper
there is also the fact that many e6300 and e6400 cores are probably faulty i.e defective cache or failed speed binning at higher levels. Intel would have locked the defective cache by severing some trace and underclocked it so it was still functional and sellable.
if it were possible (as far as i know it's not) to unlock the cache, it wouldn't do much good because it's probably faulty.
as for Russian weapons, how about Kalashnikov's genius