I mentioned turn-based combat outside of the context of IE-style games. Turn-based combat in a Darklands-style game, where exploration only occurs on relatively constrained maps with small numbers of combatants, would not suffer the same problems. I do not think it is a stretch to say that if you took all of the core content of Darklands and instituted a good turn-based combat system, it would be fine (arguably much better if the character system supported it). The maps are never particularly large and in 90% of the fights, there are less than a dozen combatants including the party. A good turn-based combat system needs to give players significant choices to make on each turn, often weighing individual tactical considerations against longer-term strategic considerations. Movement and positioning should have tactical importance. I prefer small hex-based spaces or raw distance for movement and targeting over square-based. I think it's also important to think about phase/character order, how NPCs play into that, and how those interrelationships affect the overall pace and length of combat.
That said, I think a weakness of many combat systems is that they often don't give the player much to work with in terms of character development and interesting turn-to-turn choices. Fallout had different firing modes including targeted shots, but combat generally devolved into eye/groin shots on every turn. Combat was enjoyable and character building strategies could be interesting, but the tactical combat became rote fairly quickly. Darklands gave martial characters standard/berserk/parry/vulnerable attacking modes, but you had those from the beginning of the game and the characters generally did not evolve much beyond that. Even though the Gold Box games used the 1st Ed. AD&D rules, they were a lot more tactical. Melee characters weren't particularly complex, but positioning them was extremely important in those games. Especially in Pool of Radiance, Curse of the Azure Bonds, and the early Dragonlance games, spellcasters changed a lot every two levels and their strategic resources were very valuable. Games that tightly focus turn-based combat and give the player a set of interesting tactical/strategic challenges and options can be great.