Sandbox/free-roam can work, though, if it's done right.
Technologically, Kuggazer did a lot right when HIBAH was sandbox/free-roam, but the quests/tasks were rather linear, so story-wise, it ultimately made more sense to change it to VN.
For sandbox/free-roam to work, there needs to be parallel story lines and/or quests, a proper hint system (suggesting where to go and/or what to do), and not require a lot of grinding to make progress.
It's not easy to make a game with sandbox/free-roam, so unless it's done right, it's going to overshadow everything else.
But, to reiterate, it can work, if done right.