your rear will be fine. lots of yj's run no front track bar as well but the added stress of steering in the front can and will wear your spring/shackle bushings more as well as the clamps that keep your springs in the pacs centred on each other. this can lead to failure of spring pac centering pins. all this added wear can affect steering.
get an adjustable front track bar that you can disconnect when offroad just like sway bar discos. JKS makes a nice one.
just my .02