'$b$4' will also change to '$b$5' when inserting a row. The $'s only help when pasting a formula to additional cells. I don't think Excel will automatically do what you're wanting.
A couple work arounds I can think of are:
1) Insert your cell then Search/Replace B5 for B4. (Obviously not ideal if you have a lot of different cells you want to change the references for.)
2) Insert your cell then Cut B5, and Paste to B4. (Again...Obviously not ideal if you have a lot of different cells you want to change the references for.)
3) Copy your WorkSheet. Insert our cell in the original WorkSheet. Go to the copied version, then Copy the cells containing the Formula's you didn't want to update. Now Paste the formula cells back into the original WorkSheet.
-->While this will do what you originally requested...I'm guessing though, that you will find there were actually some cells with formula's that you did want to automatically update...But maybe not...But you're probably safer if you just go just go with one of the first 2 suggestions, knowing there will be manual updates you'll have to plow through.
Enjoy,
Ken