Rabbi Shmuel Eliyahu explains why the Temple construction is being delayed:
From "Kol Tzofayich", No. 575, Parshat VaYakhel (this past Shabbat):
"Even today we all speak about the Temple in every prayer, sing songs, etc. In actuality, not very many believe that in a practical sense, the mosques will be removed from the Temple Mount. They say the UN won't agree, that the US President will threaten, that the EU will apply sanctions, that there'll be a third world war, etc. The Temple is left to just talk...[but the Torah lesson is] to teach us that the commandment is not a distant dream...it was not the non-Jew who prevented construction but the laxity of the Jews who sought to blame others...".