No Records when searching a Non-Ranged Item by description

Hi -
On Item Lookup if I try to search a non-ranged item through 'Item Description' the seach result shows 'No Records Found' but if I search the same item by 'Item Number' it displays the Item Details.
If you want to search a non-ranged item through item description you have to select the 'Include Non-Ranged' check box.

Why is the 'Include Non-Ranged' check box criteria included for item description?
Shouldn't it work the same way as item number?

Thanks
Prasoon