I think you can use the Tartakower as your main defence, but you will need to have something also prepared for:
1) QGD Exchange variation
2) Catalan
3) Colle
4) Stonewall
5) Torre (maybe)
6) Tromp or Pseudo-Tromp
7) London system
8) BGD (maybe)

I say maybe on the Torre because that depends on the move order that you choose, and same for Tromp or Pseudo-Tromp.

For example, after 1. d4 Nf6 2. Bg5 is the Tromp, but if you go with 1. d4 d5 2. Bg5 is the pseudo-tromp. Also, 1. d4 Nf6 2. Nf3 e6 3. Bg5 d5 is the Torre, but 1. d4 d5 2. Nf3 Nf6 3. Bg5 is NOT a torre, because 3. ...Ne4 is a good line for black.

Also, you may consider adopting a move order that discourages (or prevents) white from playing a QGD exchange with Nge2, because this setup is more aggressive than the lines with Nf3. You can discourage it with the move order: 1. d4 Nf6 2. c4 e6, since white may not be interested in going into a Nimzo indian, and may play 3. Nf3 here. Or you could try to prevent the Nge2 lines altogether with the move order 1. d4 d5 2. c4 e6 3. Nc3 Be7, (normal is Nf6 when white pins the f6 knight with Bg5), so now I think white chooses between 4. Bf4 and 4. Nf3.

In answer to your original question, I have no idea why the Slav gets more attention in books than the Tartakower. But possibly because they are apples and oranges. What I mean is that the Tartakower is a system within the QGD, so usually you will find it in a book on the QGD. But the Slav is an opening itself (like the QGD), not a system within some other opening. So usually you find Slav books. If in your question you meant that books dedicated to sub-variations of the Slav are more prevalent than books on sub-variations of the QGD, this may also be correct...but I'm really not sure why that would be.

Also, the list of other openings that you would need to be prepared for is pretty much the same regardless of whether you choose the Slav or the QGD Tartakower. The only difference is that instead of the QGD exchange, you would have to know the Slav Exchange...

Hopefully something here has been helpful to you.

Kevin