Thanks for the answer,
however, I must say some information are not so important as others, but, for me, for instance, RPM and number of platters have direct relation to my subjetive evaluation of how durable a hard drive is.
So, anyway, this information is rather important for me.
Let's make an example:
If the next Seagate Barracuda 7200.8 400GB match in most performace benchmarks with the Hitachi 7K400 (I guess that's how it is called), I would certainly go for Seagate, because I know that 3 platters means less risc of drive malfunction than 5 platters.
So, again, this kind of information can be rather important in some cases. In my humble opinion.