Coax directly to box vs. through face plate?
Every join in the cable reduces the signal strength. 

At 1200 Mhz satellite cable frequencies it's about 1dB for a F connector pass-thru at UHF and VHF frequencies the loss is less.

That's probably not going to harm your TV reception noticeably.
a wall plate or skirting socket is going to look better than just a wire coming out of the floor/wall, but yeah, usually you're looking at the front side of the telly, not the back.