I wish "articles" like this would be clearly marked as an opinion piece, which it is. I have not seen the new iPad Pro nor the new keyboard, so I can't comment on specifics, but it appears to have some nice features. Whether others think this is expensive is TBD, but again they are opinions. Do I wish it were less expensive -- sure!
I'm a very happy iPad Pro 12.9 3rd gen user. (I do not own or use a MacBook, nor would I consider it, although it is a fine machine.) I have three keyboards I use with my iPad Pro, two of them suitable for at the desk, plus the current Apple keyboard case. My OPINION originally was the Apple keyboard case was too expensive for me. But I was able to find one at a discount, and I love it for travel -- it's lightweight, works well for my application, and also looks professional in meetings. I would and do recommend it to others...so IMHO it really is a preference issue. IMHO if the new keyboard case is lightweight then with the extra features, it might really have a place. Honestly many other options available (at least for the 3rd gen 12.9 iPad Pro) are either heavy or clunky -- again my opinion -- and unsuitable for at least my use.