Glad you started this thread.
Dried Cow dung is used in Yajnas and poojas. The reason is that the flames from the cow dung do not exceed a certain temperature and the flames remain relatively cooler than say a gas flame. It is used for starting the homa kunda.
More importantly Cow dung is considered a pure fuel because cows eats only grass and dry paddy and other green leaves and pure water with vegetables. That is why its used in Yajnas.
A Yajnas with dried cow dung also ensures no plant life i.e. wood is wasted in the yajna. The entire Yajna is conducted from animal waste.
Panchakavyam made from the extracts of cows (one being cow dung) is also used as a natural pesticide in India since vedic times.
Panchagavya is also use as a Fertilizer. Not to mention the use of plain cow dung as excellent Fertilizer.
If that was not enough, Seeds can be treated with panchagavya before sowing. This is used for cultivation of turmeric, ginger and sugarcane and they yielded more when treated with this. Better still they show greater plant immunity.
Smoke from a dung fire keeps flies away and acts as a mosquito repellent. Most cost effective solutions in villages.
But I guess selling cow meat on-line is the only "modern" thing to do
Primitive hindooos.