I guess it is only important if you're selling your house, because the next buyer needs to have a legal floor plan,

as long as you feel that your renovation is not jeopardizing the structure of the house, it should be ok..

I renovated my hse without submitting any plans whatsoever, i even removed a few walls, not pillars though.

anyway, If your house were to collapse, due to the new structure, insurance may not cover if you did not submit the plan. thats about it i guess