Regarding the conditions required for the bracket to appear, it would be nice to have an option to omit the bracket in a beamed group when the separations are already explicit (different rhythm value or secondary beam split), like here (Ravel, Durand)
or here (Chopin, Wiener Urtext)
These figures in Dorico with the “only when necessary” option:
That said, the team surely has bigger priorities — and I created a shortcut to hide tuplet brackets anyway, so it’s not really an issue on my end!