For WWI aviation modelers, I think the popularity increase you spoke of is primarily a result of two factors: one, the Wingnuts Wings release. Eduard had probably the most respected, accurate and easily built D.VIIs in 1:48 a few years back. They didn't set the world on fire. Good models, but they didn't leap off the shelves. The Wingnuts Wings versions are much more detailed and better engineered and include better marking options and decals.
Two: Most experienced WWI modelers have come to terms with rigging. There are, of course, many ways to rig a model airplane and if one has more than a couple WWI aircraft under one's belt, rigging is no longer a serious issue. A pain, sometimes, but not rocket science. The D.VII has little rigging which is a draw for modelers who want to try a well made kit that doesn't require a lot of it. Hence, I think, more modelers are giving WWI modeling a go with the new Wingnut Wings D.VIIs. Being an iconic fighter of the Great War doesn't hurt either.
Outside of the modeling community, I think the most recognized and popular WWI fighter is the all red Dr.1