Why So Few?
That's a pretty short list
What was the last truly memorable turn-based (TB) game you've played? Odds are, it's Alpha Centauri. Perhaps Civilization II, an SSI Gold Box RPG, a SSI/SSG war-game or one of the Jagged Alliance games. That's a pretty short list, all things considered. After all, it covers four separate genres. You have your classic strategy games like Civilization and Alpha Centauri, then there are tactical combat games, like Jagged Alliance and X-Com, war-games (historical or fantasy) like Panzer General and Warlords, and finally RPGs like Curse of the Azure Bonds or Death Knights of Krynn.
What's wrong then?
Naturally, there are many more turn-based games which were released in the past decade, but that list is the cream of the crop. Take a close look: most of the games mentioned on this list were released in the early '90s. Some were merely sequels to games released in that period. As the decade progressed, fewer and fewer TB games were released.
The 80s were arguably the heyday of the turn-based game. Computers then were powerful enough to produce quality turn-based games that were fairly deep and complex, but those same computers didn't have the power to run those games in real-time. Oh, we had our action games and even somewhat complex flight sims, but major strategy games and RPGs? How could a computer handle all that, plus the interface necessary? Nevermind the players who would be overloaded with information. No - that was out of the question... at the time.
Oh, there were a few - very few - attempts at real-time that really caught the public eye. Sid Meier's Pirates! for example, was released in 1987 for the PC. The player steered the ship in real-time across a map of the Caribbean, and sea and melee combat occured in real-time. This was the first real-time strategy/role-playing game that I know of.
It took another great designer - Will Wright - before SimCity was unleashed on the unsuspecting public in 1989 - two years later. Yet, not much notice was taken that it was a real-time game. After all, SimCity wouldn't make much sense in a turn-based fashion, would it? It's only natural that most people didn't take any notice of how it was played. We were becoming accustomed to realtime gaming already, before the '90s even started. Of course, SimCity was like no turn-based game before it, which made the transition easier.
Actually, it's not hard to imagine a turn-based SimCity. A seasonal, monthly or even weekly turn, with the city updating its graphics to reflect how populated it is - that could work, right? After all, the only difference between a turn-based and real-time game is the size of the turns, and the fact that a turn-based game makes the player hit 'next turn' (or an equivalent), while a real-time game goes through each turn in the same amount of time. However, while one could even deal with monsters and natural disasters... one factor would be lost - the fun. How compelling do you think SimCity would be if you had to hit 'next turn' five times to see the results of some action you made?