There’s a major problem with these in parts of India, where certain painkillers that are often administered to dying people for palliative care are toxic to the carrion birds that are supposed to consume them. So populations of the birds have been dwindling and many of these towers are full of decomposing corpses that are left to rot a lot more slowly.

Other than the fuel needed for the incinerator, I don’t see what’s wrong with plain old cremation.