I think they are extra strong in closed positions. After the center is traded off, the once blocked in useless bishop is all of a sudden ready to strike without warning. Its like a rogue going stealth waiting to ambush and stunlock your king.
If you think about it, the king is one of the weakest pieces on the board. What kind of king runs from battle? We need to upgrade the king to become the strongest piece on the board; after all, a strong army needs a strong leader. I propose giving the king all the moves that a queen can make in addition to the knight jumps. Make chess great again.
That would make it too hard to checkmate the king. But maybe the knights should have some kind of charge ability on a cooldown of a few moves or something? Pawns have all kinds of cool abilities like promotion and on proissant.
And no, I find fianchettos quite weakening. Once your bishop on the long diagonal gets traded, the colour of that bishop becomes very weak, and even more so if I have a bishop of the same colour still on the board