I can’t prove it with pasukim, but I have a different way of looking at our seemingly endless exile.  The common explanation  is that we didn’t live up to the standards required for the persistence of the Holy Temple.  Eventually we’d used up our chances and, failing, saw the destruction of the Bet HaMikdash and the loss of our land.  If only we can regain the spiritual level we occasionally reached in those long lost days, we’d earn the return to our land and, shortly after, witness the rebuilding of a Third Temple.  But, obviously, we have been too flawed, generation after generation, so we remain in this limbo.

My thought is that we did, with each of the two previous Temples, create a suitable environment for them.  However, the plan has always been, סוף מעשה במחשבה תחילה, Sof Ma’a’se B’MachShava T’chila, the final reality is the original goal.

In other words, the third Temple, may it come speedily in our days, will be overwhelmingly more beautiful, more powerful, more love-filled than either of the two previous ones.  Therefore, our world needs significantly more work to prepare for something this grand.  Therefore, it’s not so much our shortcomings we should focus on, but at the enormity of the task which will bring even greater reward.