First of all, drafting and developing a league average player at any position is not easy for any team.
Secondly, high contact hitting, high OBP, and better than average defense are tools.
Thirdly, the failure rate on any baseball draft pick, including the 1st round picks, is so high that if you get an above average player from any pick you are beating the odds. If Madrigal becomes a regular, he will have outperformed his draft position historically. That enough is worthy of the pick.