I've spent decades reading and watching Rick's various creations. It's amazing to watch the great things he's done, and also to see the gaps that are big enough to drive an ICE train through. He does seem to love simplifying European regions down to stereotypes. A quick phrase that encapsulates the region, plus a food and a drink, and he can repeat it like a mantra. Yet it seems like he doesn't care about food being good, just local and quaint.
He ignores most natural beauty and physical activity (other than walking). He is uninterested in nice livable cities (e.g. Hamburg) that aren't filled with A-list sites. He talks about slowing down and being a temporary European, but his tours spend so few nights in any one place that you're constantly unpacking and repacking and getting back into the bus.
But he's done some amazing things. Crafting self-guided walking tours in his guidebooks, both of cities and of museums, adds so much depth to traveling without a guide. And if you want a guide, he has established connections with guides even in small towns and plugs them. He focuses on the transportation, how the ticketing works, how to get to sites, how to get between towns. It removes a lot of anxiety.
The big thing is his notion of a guidebook being "the best three weeks" in a country. I've looked at both the Rough Guide and Lonely Planet for Germany, and although they certainly include more than he includes, their guides are not often filled with huge adulation for places that Rick omits. None love Frankfurt, although they give more suggestions. Rick oversells Rothenburg, but so do other Germans. It's not as if the tourist hordes there don't include Germans! And certainly most Americans will prefer strolling a small italian village in Tuscany/Umbria to strolling one in Northern Germany. If Rick started selling a Small Villages of Non-Bavarian Germany tour, it would not sell well.
If you take Lonely Planet or Rough Guide and strip them down to three weeks of touring, you get something like Rick's guide. Except Rick can include MORE details about those places he likes because he entirely omits those he doesn't like. I enjoy the contradictions that are Rick almost as much as his guidebooks. He seems like a preacher, his flock are Americans who enjoy Europe but find it intimidating, and his message is to overcome uncertainty and explore Europe. By simplifying Europe he makes it easier to sell Europe to ignorant and insular Americans. I am an avid traveler, so I'm not in his intended demographic, but I find a lot to learn from him anyway.