Two perspectives, I think.
Some would think they are just the caretakers of this era, therefore their job is to preserve the blade in the best condition for later peoples.
Others would think nihonto is an art but also a weapon, limiting its usage only as an art would be bit of waste.
I personally have always thought nihonto as an art AND a weapon, well due to my historical reasons, so I do understand your point.
If nihonto is only seen as an art shouldn't fancy shinto or shinshinto have much more value then how they are seen as then now?
A weapon, that was made to harm people.
An icon, that was made to show gratitude and promise for another.
An art, that was made to study and appreciate its form.
And a pride, that was made to show one swordsmith's lifetime earned skill.
These are all shades of nihonto.
If one is going to use it properly(not as a some kind of a joke) I'd say sure why not? The choice is yours.
Just remember koto is likely to be weaker than nowaday's steel blades.