Question is: why? Original mix of the comedy, romance, cosplay, slice of life, ecchi was just right. Why suddenly ignore all the other elements. We have a whole lot of DIY-style manga and anime, about fishing and other activities and stuff like Yiru Camp that's basically an advertisement for outdoor activity and camping, ,making manga and anime, but none of those forgot to add other element to the story, to make it more fun to read.Wrong way around. It was a clear old-school romcom manga, with cosplay being the plot device used to push the romance along (bringing them together, keeping them in close proximity, etc). At some point, the author decided he was going to switch genres and just dropped the romance and comedy from the series entirely. Now it's a series dealing with a 15 year old boy's depression, where he takes cosplaying far too seriously.
Yeah, we occasionally have things like Runway de Waratte, but those are very clear about their focus on actual theme, without almost any side-stuff.