If a player provides no defensive value, the bat has to carry the whole profile.
Recent “can’t miss” bat first picks like Alec Bohm (#3 overall in 2018, 1534 PA of 99 OPS+, 0.7 career WAR), Andrew Vaughn (#3 overall in 2019, 1392 PA of 103 OPS+, 0.5 career WAR) or Spencer Torkleson (#1 overall in 2020, 771 PA of 85 OPS+, -1.2 career WAR) are the highest profile recent examples of how big of an ask that is.
Hiura was supposed to be the safest bat in his draft class (and hey, his 1.5 WAR is still the highest of any 2017 1st round hitter), but with no position to play and streaky offense it’s hard to stay in the lineup (or MLB) to get consistent playing time.