This is cool. 40 card decks are great! In addition to being physically ergonomic, I find 40 cards to be a fun deck-building size. With about 17 lands, you get 23 choices to make of what to include outside of that, which feels like a sweet spot between deck-building expressiveness and decision fatigue.

As an aside, I'm convinced that a big reason WotC (and FLGS) are pushing commander so hard is because 100 card decks means you get to sell more cards.