I think the reason that the soft-weakness and pseudo weakness works better here than in p4 is in big part because it doesn't overstay its welcome. Other than that since it is a boss fight you have some expectation/allowance for the fight to bend the normal rules of the game a bit and there is some expectation of possibly loosing and having to redo the fight letting you properly discover the mechanic and utilize it as a deliberate part of your strategy. If you have the mechanic appear in random encounters it is more likely to be percieved as a hassle since it slows down the generally fast paced random encounters and therefore it sticks out in a negative way.
I think the reason that the soft-weakness and pseudo weakness works better here than in p4 is in big part because it doesn't overstay its welcome.
Other than that since it is a boss fight you have some expectation/allowance for the fight to bend the normal rules of the game a bit and there is some expectation of possibly loosing and having to redo the fight letting you properly discover the mechanic and utilize it as a deliberate part of your strategy.
If you have the mechanic appear in random encounters it is more likely to be percieved as a hassle since it slows down the generally fast paced random encounters and therefore it sticks out in a negative way.