What a lot of you seem to be missing is that the R5-2400 will be the premium product available at the top of the stack for uSFF desktops that can't fit a dGPU. The only step up from it will be the MUCH more expensive KL-G chips. From that perspective, and in that market, they actually have a lot of pricing flexibility there. I think, given that niche, which is a non-trivial segment of the market, it is justified for where it is.
When comparing it to non-APU chips coupled with dGPUs that are in the cost leader catagory (RX550/GT1030s) where they are selling make volume over margin, it will never shine. You can always scrape the bottom of both stacks and make a system that will cost a bit less for the performance. The APU makes the most sense where it is inconvenient or impossible to use a dGPU or AIB. Given that constraint, I think that AMD could even charge a bit more for the part and still do well. It would also be a great part for the desktop AIO market if that was still a big thing. Apple could put it in lower end iMacs and make a killing with it.