Don't get me wrong, Persona 4 is definitely an improvement. The reason I'm defending Tartarus (and Persona 3 in general) is because it came first and set the template for the Midnight Channel. It's why I argued that people should play 3 before they play 4; 4 has better dungeons, better gameplay and better social links, but that's because it had all the groundwork laid by 3 to build on. To get the full experience, I would advise playing 3 first, because you'll get a great game, and you'll enjoy 4 a lot more from having the comparison.
I agree that Tartarus suffers from a case of quantity over quality, but I think it fits into the story just as well as Persona 4 did. For most of the game, it's essentially a training ground that provides a way to level up for the full moon bosses without having to grind. The general rule is that if you can make it to the highest point within a given month, you're ready for the boss fight. Plus, taken as a whole, the game literally could not happen without Tartarus. It has a crucial role in the story that ties in naturally with the dungeon crawling gameplay.
You had a lot more freedom with Tartarus than you had with the Persona 4 dungeons; it didn't take up after school time so it didn't interfere with the majority of your social links, and you can move through the floors a lot quicker thanks to the less restricted layout of each floor and being able to split the party. Plus, there are no annoying gimmick floors like the ones in Void Quest or Striptease. It also didn't cost a fortune to heal, either.
Finally, getting back to the subject of getting killed, I think we can all agree that what these games really need is for them to not game-over you when the player character goes down. Just let us revive them with the other team members, that's what healers are for.
