Well you have to consider the demographics of the show and what they appeal too (unintentionally)
SU appeals to the tumblr crowd due to the 'social norm destroying aspects' that are intentionally there for character building that may come off as preachy. It…while I can't really objectively say this with educated certainty, seems to try to ground itself more in 'reality' than Star in a way in order to make a statement. Star just has drama, but it's drama that is relatively non polarizing and has been done before (not that SU doesn't have that either).
Voltron might not be annoying (haven't seen it) but from what I garner from all the fan art I see it tends to be picked up by girls who like their yaoi…kinda like a derivative of SU's fan base mixed with the Yuri on Ice crowd.
Star does those things for comedic purposes and the fan base is sorta aware of this based on the tone of the series. Not that Su doesn't do that either, it's just that both shows have different forms of expression in a way and can be interpreted differently and attract different people.