I don't think it's a case that everyone else is weak right now. If Australia is far worse than we have been historically and we've still been there or thereabouts as the second best team in the world in recent years then effectively you're saying that every team in world rugby is crap and New Zealand just wins by default.
I think it's far more likely that New Zealand do have a great team right now.
To take a random 'great' All Blacks team, let's look at the team that beat Australia 30-9 at Concord Oval in 1988. This was during their previous undefeated reign (that they matched before losing to England).
15 - John Gallagher
14 - John Kirwan
13 - Joe Stanley
12 - John Schuster
11 - Terry Wright
10 - Grant Fox
9 - Bruce Deans
8 - Buck Shelford (c)
7 - Michael Jones
6 - Alan Whetton
5 - Gary Whetton
4 - Murray Pierce
3 - Richard Loe
2 - Sean Fitzpatrick
1 - Steve McDowell
If you look forward a year you could add players like Graham Bachop, Zinzan Brooke, Ian Jones, and Walter Little to the list.
How many of these players would you slot into the current All Blacks side? Michael Jones, Buck Shelford and Grant Fox are the standouts from this team and you'd have to argue pretty hard for any of them to be ahead of McCaw, Read and Carter.
Fitzpatrick is an AB great but so is Mealamu. At their best, it's pretty hard to split them.
I think there is very much a theme of rose coloured glasses whereby everyone thinks that the All Blacks and Wallabies were much better in the past and the current lot are average and are only on top because Australia is so bad.