Why are Muslims not granted rulership and leadership of the world,Allah has promised in Quran but deficiency is ours

Allah Pak says in Quran Surah Noor Ayah no 50

"Allah has promised to those from amongst you who 
believe and do righteous deeds that He would surely 

make them His vicegerents on earth."
Moreover, it is Allah Ta'ala's own obligation to grant 

every help to the true Muslims and it is also His promise  
that such people will always remain exalted and glorious.

This is borne out by the following verses:
"And it is our bounden duty to render succour to the 
true be1 ievers. " (Surah Room 47)

"And do not give way to despair, and do not grieve, 
and you only shall dominate, if you are true believers."(Ale Imran 139)

"And honour is only for Allah, His Prophet (sallallaho 
alaihe wasallam) and those who believe." (Al munafiqoon 8)

Why are Muslims not granted rulership and 

 leadership in the world?  EVEN IF THEY GET IT REMAIN DOWNTROWN AND WEAK under someone else control.

Maulana ILYAS EXPRESSED his view in these words: 
"When we do not fulfill the commandments of Allah and refrain from the forbidden in our personal lives over which we have full control and there is no obstacle or compulsion, then how is it possible that we be entrusted with the governing of this world. 

It is only through the decision of Allah that the believers may be granted government on the earth so that they may seek His pleasure and establish His laws in this world. 

Now, when we are not doing this in the sphere of our own choice (in our individual lives), how can it be expected, when tomorrow we are given the reins of government. we shall do so?

May Allah help the Muslims