Very dangerous and should be avoided. You will be unable to check the condition of your floor annd won't know there is a problem until your horse has its leg ripped off by the moving wheel. So no, not worth it!
Interestingly, I have completely the opposite view. I have the same body for my lorry that I've had for about 18 years. We laid liquid rubber flooring when it was converted initially. We are currently putting the body on a newer chassis, and the completely sealed floor has done it's job. The floor is in tip top condition, because it's never had any wet on it.
Maybe I'm lucky that my dad is a mechanic and perfectionist, and it was done properly in the first place. I'm fairly certain Dad will also have checked the floor from underneath every time it was being checked before it's MOT, which might be harder to do in a trailer.