deep trans pan for 904

In line with this topic I have a question. Why do you need the 1" spacer for the filter and would do you need to change dipsticks? I would think that if the pan is just deeper, then it should not affect where the dipstick should read full as that level should remain the same and if this is the case your filter would still draw fluid as it would still be submerged under same level of fluid. Am I missing anything here?