The problem

Not protected, brickwork will absorb soil moisture.
therefore problematically:
due tu capillary effect, water will flow through the whole wall and will evaporate
Water naturally rises upwards, brickwork works as a pump
Salts, carried with the water, infiltrate the brickwork
those salts crystallize and show at the wall`s surface
Without effective rataliatory action the aftermath is forseeable and hardly to eliminate
Paint and wallpaper will peel of the wall, also plaster
brickwork will be destroyed irresistably
structural-physical and static damages will arise
heat insulation will be diminished and heating costs will rise
health risk will increase e.g. by mold