why is the identity resetted after a truncate? For me is a possible source of inconsitency.
As Lokesh has already explained, resetting the identity seed is a characteristic of the 'truncate' command. If you want to retain the seed then you use 'delete' instead. So, there's no inconsistency, it is just a case of using the right command according to your needs.
At least you learnt something, so from that point of view it is a good question. ;-)