Well one of the biggest complaints people had toward Let's Go was the decision to go back to Chibi graphics. I believe overally everyone was very fond of the more "realistic proportions" of ORAS and eventually gen 7 games.Interestingly the character models look closer in style/proportion to that of the S/M models, but with higher quality.
Doesn't really surprise at all that they decided to keep with realistic proportions, I hope whatever Pokemon is visible in overworld due to them being doing stuff around and obviously in battle also is on realistic scale as well.