I don't think boring gameplay is a quality of TB systems per se.
Its more a result of not having guaranteed healing (or at least notification) before a boss when it all comes down to it. Because you don't get healed/notified you have to conserve resources on the chance one comes. That means random encounters can't require those resources, a low random encounter rate under that would mean you'd have few really long and boring attack-fests, so you have many, quickly dealt with encounters. The need to conserve resources also works against strategy in turn based systems, since the actual strategic part of the system nearly always requires resources (and this is why ARPGs seem more involved, even with no resource use you have a variety of normal or recharge based attacks).
There's been some fairly impressive turn based stuff where you're guaranteed to get all resources back after a battle, and each encounter is challenging. There's other that take a more traditional approach but the different in boss and random encounter power is reduced by increasing the latterr and reducing the former, so that resources are better used throughout but still being measured.
A strength of turn based is that you can have multiple characters who each play as important a role in combat as any other. In ARPGs AI-controlled party members are always going to be less useful. Turnbased games where you don't have party members or have party members and can't control them are generally poor in my experience, its what I disliked about Persona 3 , and FFXIII. Likewise ARPGs are well suited to single character games.
My mixed feelings more spring from largely accepting that Final Fantasy no longer has any interest in my tastes. XII demonstrated it nicely and XIII continued on further in the same direction.
