Itīs true that this kind of all out weapons practise is good for developing a strong, immoveable and pliant center for both Uketachi and Uchitachi. Afterall hitting two pieces of wood against eachother at full force is more constructive than smashing your trainingpartners spine into the matt at full speed.
But basic suburi and basic partnerpractise skills have to be mastered before going all out in weapons. Othervise it would lead to injury- were not talking about kendo, we are talking about weapons practise with no body protection against a heavy oak weapon with no tsuba.
So timing, blending (awase) and correct maai becomes quite important- because you donīt want to get hit
in the first place- just like when you are dealing with a real (sharp) weapon.
Getting smashed into the mat is kind of part of martial arts training, in my opinion. I actually love it. I'll be honest, it's hard to learn a technique (or a variation on a technique) when you train with someone you can't go all out with. I'd go as far as saying that it's harder to properly do a technique with someone who attacks you slowly than with someone who comes at you full speed. Someone who comes at you full speed gives you a lot of energy you can work with but at the same time makes sure you don't get much time to think. It's do or die, so to say.