What's more, he thinks that's somehow an insult.
There's nothing wrong with being a casual game, and Horizon does it really well IMO. It's great as a pick up and play, and there's enough depth there as well for people who want to take it super serial.
And yeah, like every other game that becomes popular it largely carries over the things that were successful to the next iteration. A developer would have to be morons not to. As such, yeah, games can feel a bit like more of the same at times, but for players that enjoyed those early games that's generally considered a positive. No fan of the Horizon series wants to throw away the good parts of FH2 and 3.