Side stuff being a failure is something that one can say in hindsight of it. (After trying it out; Eureka for example was a failure for me)
Right now I have not much more to do in 4.3 than I had in the 3.1 patch. I still can only run one new dungeon/raid/trial and the older ones, I still can only do daily beast tribes and the rest is all something that will only come later. The only parts that adds a bit more to the patch is the Doma reconstruction and the new delivery quest but that is nothing huge. Both of them together will take like 20 minutes per week.
It might be that more will come in a few weeks/months but that does not change it that for me the initial 4.3 patch was boring. They could have put the new palace in it and my opinion of the patch would be quite different, since the old palast was something that busied me for long hours and I can see the same happening with the new one.
Just because the MSQ is better (which is subjective) does not change the substance much. Its still a once done deal. People could also argue that the trials are getting to easy and that Thordan might have been a nice challenge that could keep people playing it longer. 24 man is also subjective and something being a bit more difficult does not give the game more substance..because that would mean that creating a 24 man on savage levels would give the game huge amounts of depths.
Crafters and gatheres always have stuff to do if new items come out and the roulette is only just another way to run old content.
Again we are talking about real new content and there the 3.1 may have had more. Diadem 1.0 was new content and was even longer alive then the second version. It was a failure in the long run but it was something new, the same with LoV. So if we look at the patch without the hindsight of "x was a failure" and just pure content, 3.1 had still more.
If we compare the whole 4.3 with all the other still coming patches than this might be more than 3.1 but we are just comparing the original 3.1 and 4.3 without the .xx patches. And there I dont find more to do.