Is building models "art?" Good question.
My first college art class was called "Studio Foundations 1." Basically, "how to draw in pencil." The teacher stated he was teaching us how to draw, but that skill alone didn't make us artists. I tend to agree with that idea, but the definition of "art" is incredibly subjective. Here's my very subjective opinion ( not trying to say I'm an authority here, so please read in an "IMHO" wherever applicable ).
I recognize scratchbuilding as art in most cases. These people take raw materials and build their vision of the subject with few if any pre-built parts. That qualifies as sculpture ( therefore art ) in my mind. The biggest exception in my mind is in effects model-building. The goal is to produce someone else's design for the screen, not be creatuve ( except for the obvious problem-solving involved ) for the sake of self-expression.
Kit-based models, even with aftermarket enhancements, are a bit more tricky. Straight from the box is not art. Kitbashing is rarely art. That's not to say that they're "just making toys" or "not serious." I think of these as "craftsmanship," not "artistry." It's like a carpenter building from plans.
Where building models crosses into art is in the dioramas. The thought and skills that go into a well-done diorama involve more than faithfully recrating a subject, they involve trying to capture a moment in time and the human element, whether factual or fiction.
I've never referred to any of the models I've built to date as "art." Even with what cusomizing I occasionally do, it's no more artistic than a paint-by-number project. I put a heck of a lot more *craftsmanship* ( sorry, can't get italics this time ) into my models than a paint-by-number would demand, but that doesn't make them "art."
But, as always with art, It's in the eye of the beholder. This is just my point of view.
Have fun!
I couldn't even find my way back to "normal" with the Hubble!