There's nothing theoretical about it. The value after depreciation
*is* the nominal value. What you mean is that in theory the nominal value ought to reflect the *actual* value, i.e. what the item would fetch if sold.Well, it's all a question of what the purpose of your accounting is. If it's just for tax purposes, then your approach is fine. It means you won't need to keep track of the tax WDV separately from the accounts, since it'll already be in the accounts.
But if you also want to keep track of (a more realistic estimate of) what your capital equipment is really worth, then you *might* be better advised to use a depreciation method which differs from the tax WDV method. But if in the grand scheme it's not going to make an awful lot of difference, then there's probably no need.