Woeful pathfinding and ‘running around like chickens’ aside, it doesn’t actually sound like we need to throw out the chain system entirely (as that does work well on consoles where multi-selecting would be clunky). What would help is:
1) A command to chain/unchain all with no range limit
2) Stealth to apply to all currently chained party members (I can’t think of a situation where you wouldn’t want to stealth any of the PCs following you if you’re going into stealth yourself)

I actually don’t think formations are too important for a turn-based game like this. In fact, having all my party frog-marching around doesn’t feel very D&D to me. I’d rather it went more the other way, like Dragon’s Dogma’s pawns, where they have a bit more independence and your druid might automatically harvest plants for you while you’re walking around, perhaps your barbarian likes smashing crates and saving you having to check all the containers yourself (all within reason of course, and hopefully with better AI and inventory management). To me that cuts down on the repetition and feels far more immersive. Gives you more opportunities to have companions say things too, making the game feel more alive.