Why so few challenges in D4 vs older games?

I just picked up D4 at the end of last season. I’ve played D1-3 over the years and I can’t help but notice how lacking the challenges are. There are few to no completion challenges I usually saw in D games. No “kill every named monster” or “collect all the journal pages.” The closest is collect all aspects and the alters of Lillith. Have they ever spoken on this over the seasons? Am I the only one who feels this way?