Trust: These barbells are not going anywhere
Adjustability: You are either the “right” height, or you are not supposed to use these.
Incremental adjustability: Divisions/differences in weight have been (arbitrarily) predetermined.
Security: (see “Trust”)
Visual + Spatial sense of progress: As you increase in strength, you physically progress to a new set of barbells, which increase in weight along a continuum.
Safety: With a limitation of height comes a (planned?) corollary limitation of users’ ages, preventing those unable to reach the bar from using these (though also excluding mature individuals who are “vertically challenged”).
Better? Worse? Subjective.