Key's history is a deep topic. That review of Little Busters is on point. Even before Little Busters, Clannad's After Story route was criticized by some for being too similar to YU-NO. When I watched one HBR trailer in slow motion, I could even see which character is the first to be sacrificed by Maeda... and it's the type of character he often chooses. He's actually self-aware that his ideas aren't all fresh: the story concept for Summer Pockets came from him, but he had hesitated to put it forward because he said it felt derivative of his earlier works. Still, Key wanted to use it, and SP sold well anyway. I liked SP too; a story doesn't need to be completely original to be enjoyed, and if HBR ends up anywhere near SP's level that would still put it in a league of its own among social games. Above all, Maeda still has strengths as a comedy writer and as a character writer; Kyousuke from Little Busters and Kanade from Angel Beats in particular are timeless fan favorites.
At the core, I guess VNs inherit the advantages and disadvantages of books. Most people just don't want to read books, unless there is something abnormally good there which they can't find elsewhere, or everyone around them is reading a particular book too, like Harry Potter (or Kanon, Tsukihime, Ever17). They prefer movie (or anime) adaptations of books. The English-based VN community never had a bubble, and so like you said, relatively speaking it's done well for itself in recent years, with DDLC even on Famitsu's cover the other day. But in contrast, the Japanese VN industry is expected to financially sustain a good number of companies that aren't just indies and localizers, and sales aren't what they used to be...