Researcher: Taliban pressured by Arab donors to destroy Bamiyan Buddhas
Good question: Why did the Taliban allow the Buddha statues to exist for so many years? Answer: The fact of the matter was that local muslims, even the local Taliban, liked the statues very much and integrated them in their belief-system. As far as my sources (for example one Afghan Anthropologist) describe it, they thought of them as powerful "spirits” which they respected and which "had always been there”.
The local Taliban leadership refused to destroy the statues, officially for fear of an upheaval of the local (also very superstitious) population. They feared to lose their support and that the destruction of the statues could lead the population to turn against the Taliban.
Finally, the local Taliban leadership was replaced by cadres from Kandahar. The latter executed the orders from Arab "donors” who had threatened to stop funding the Taliban’s cause (we are talking about at least 2 to 4 billion dollars per year – for a country which had a GDP of 12 billion $ at the time) if the statues were not destroyed. Of course, the Arabs considered the statues to be of "kafir” origins and that it was heretic, that the locals accepted them. However, this was not the main cause for their destruction:
The Taliban government tried time and again to be recognized as the legit government of Afghanistan – especially by the US. Bill Clinton was not unwilling to grant such a rapprochement if he could force the Taliban to move on some issues and if he were able to protect and advance US interests in the country (Hamid Karzai was working for a US oil company at the time). The Taliban leadership around Mullah Omar was definitely open to this, as they saw it as an opportunity to strenghten their grip on the country. They could concede a lot in talks with the US and still do whatever they liked to inside the country.
Al-Quaeda and the Arab oil-money-guys were very vary and decided to torpedo these efforts for fear of losing their influence. The destruction of the Bamiyan Statues was only one of many activities they initiated in order to circumvent the US and the Taliban governments to create closer ties or even official recognition. And it "worked” – the world was shocked at the barbarism, not only in Bamiyan, but in the whole country and all the Western governments distanced themselves from, and condemned the Taliban government.
"Note 124: Reportedly the Afghan Taliban were not really interested in the destruction of the Buddha statues. However, their Arab donors exerted pressure and threatened to reduce funding if the Taliban would not comply and destroy this world cultural heritage (Tarzi, 2008, p.306).”
([Tarzi 2008] Tarzi, Amin: "Neo-Taliban”. In: Crews, Robert (Hrsg.); Tarzi, Amin (Hrsg.): The Taliban and the Crisis of Afghanistan. Harvard University Press, Cambridgea, 2008).
Read the whole thesis: ”Changes in the Pashtun tribal structures since 1978: the influence of war, foreign militaries and militant political Islam"