But Apple managed to make the 2018 iPad Apple Pencil-compatible while actually lowering the price instead of increasing it, even though the iPad has a screen that is much bigger than the trackpad of the MBP. So realistically, would the price be an issue with 1500+ € laptops here when adding the Apple Pencil tech still allows them to bring down the price on products that already have a much cheaper price point and a larger useable area for the pencil?
Admittedly, I don't know much about the magic that Apple uses to make the Apple Pencil work as great as it does, so maybe you're right and there are some obstacles to overcome. But the technology behind Apple's touch screens is not so different from their trackpad technology so the price doesn't seem like a reasonable counterargument to me.
If anything, I'm sure there are people who would rather pay a small price-up for Apple Pencil support than for the Touch Bar, namely artists and designers who need to make a lot of digital drawings. Dedicated digital drawing pads for professional work can cost hundreds of Euros, so even if Apple Pencil support would be so expensive that Apple wouldn't put it in as a standard, I'm sure many people wouldn't mind paying 200€ or so extra as an upgrade option for Apple Pencil support to get an excellent drawing pad built right into their MBP.