Other games in this genre handle it by tying your MC directly and intrinsically to the core plot of the game in a way that the other companions are not; this gives them a very good reason to follow and ultimately defer to the main character's decisions - the MC is deciding for themselves how they will approach the issue that personally affects them, and the others follow because it matters to them, or because they think helping the MC best serves their interests, or any other reason circling that - and for the most part this core reason is *more* pressing than their personal objectives, which is why they continue to follow and wait on their personal objectives until the MC diverts time and energy to help them out. The important element that is unique to the player character must outweigh any one individual goal or need of the other companions.

The tendency of other games in the genre doing this, for generations of games, is not an arbitrary decision; it serves an important purpose which Larian's game is currently missing.

Suggesting "Oh the MC will have an important role to play, it's just not been revealed yet" is not good enough. It Needs to be clear and present Now from the outset, as the catalyst for why our other companions are followers and not leaders, and why they are willing to put their personal directives on hold until we get around to them. (NWN2's knight captain is a good example of this principle; the unique element is introduced from the beginning, and while the other companions and NPCs all have personal stories and personal goals and quests, and as important as those things are to them, they recognise that the thing that the shard-bearer has going on is more dire and more important, and so they choose to follow us, help us, and wait until we can all find time together to help them with their own objectives.)

Without this, it's a gaping great plot hole that shatters any hope of immersion in space and story - as a lot of folk around here have been pointing out from day one. "We've all got a tadpole and we all need to find a cure so we should stick together and do that" is a perfectly good reason for them all to stick together, and travel as a party, but it's NOT a sufficient story hook to explain why our player character is made the defacto leader of the group, in amongst all these legendary-epic-heroic individuals... not on its own.