I suppose, reading through these comments, I get why the author would wrap it all up suddenly even if her health wasn't an issue.
This was a cosplay/doll manga about two passionate people supporting each other, at its core. The romance was always a B plot. I buy the volumes, I read all the author notes about all the dedicated research put into all the hobby subject matter. The long struggle about the correct material and the pitfalls of perfectionism were all part of that.
But all I'm reading is people upset about all the boring cosplay stuff getting in the way of the romance and that makes me sad.
"Not outstaying it's welcome" when the most recent arcs had set up a multitude of plot threads (StormSen made a pretty good list several pages back). It was just amping up again for something big.
My disappointment is complicated. I'm sad it's over so suddenly, I don't expect the epilogue will really do much to change that.
TL;DR It's a shame the hobby manga ended like the romance was the focus all along.