Where have the tactical turn based games gone? Simple: it is no longer financially viable to produce such games. We're in the world of FPSs and genres that have "action" prefixed to them (ARPG) and everyone wants eye candy and gore and action and adrenaline. Sitting back and thinking for minutes on end (oh no, not minutes!) about the next turn is becoming (or has already become) the province of the stodgy curmudgeons that are the older gamer generation. While they may be numerous and have the disposable income to fund such games, they no longer have the time to commit to them ... certainly not in volumes that accompany the halcyon days of the younger generation.
I'm a proud and ancient curmudgeon, and let me add that I created a mage in WoW named Curmageon, and according to the WoW armory, I'm the only one of us 10 million losers who thought of that, and what does that say about me? But to continue, as a Jagged Alliance 2 fanatic, I can think of no happier fantasy than a return of some turn-based strategy goodness. I mean, even those Paradox games like Hearts of Iron, etc are ostensibly in real time (and they do succeed, but because or in spite of is debateable). But tactical combat especially benefits from the time to consider, for the coordination of each character's precise position and perfectly-timed special abilities.
Anyway, I can think of no happier fantasy. But classic PC gamers have to be hardened realists by now (or at least had ought to be), and we recognize that a fantasy is just a fantasy. There's been a new generation, far more numerous, who don't object to swords and Orks and fireballs; but they do find it hard to understand why that particular band of Orks stays frozen in absolute stasis for the 10 seconds it presumably takes the mage to cast his fireball spell, or why that fighter stands perfectly still while another group of Orks advance one at a time to a square next to him, and take exactly one swing each.
Turn-based gameplay is an abstraction, it's a game mechanism that's heavy on the game, and as computers have gotten mightier, the trend in ALL things is towards more "realism". I know, we're talking about Orks and fireballs, but one of the key differences between us (the Western world) and the Japanese is that we (as a game-buying public) are only willing to suspend our disbelief so far. We can imagine a world of Orks and fireballs, but a world of turns?
This is just to say that while I cherish and prefer turn-based tactical combat, I can also see the (majority?) viewpoint that turn-based gaming was an abstraction that was tolerated only because PCs lacked the power to render believable combat in real time. And now that the power is there, real-time is the only acceptible mechanism; exactly the way people feel about 2-D v 3-D. To that viewopint, turn-based's time has passed, and they say, 'good riddance'.
What can ya do?