Unless you were born into the landed gentry (and I certainly wasn’t) then the chances are that a great many of your forebears were tenant farmers or agricultural labourers, who would have depended on animals to carry out manually intensive tasks, tasks which have now been mechanised by technological advances. Similarly, previous generations would have depended on animal skins to provide them with clothing and footwear, but the availability of good quality synthetic materials means this is no longer necessary; although leather is still widely worn, there is no need for it to be.
Being vegan in more than just a dietary sense is now easier than it ever has been and this is due to technological progress. The petrol-driven internal combustion engine replaced the horse-drawn stagecoach, though one could put up a reasonable argument that the latter is actually more environmentally-friendly in cities suffering the effects of traffic pollution. Nylon was developed as a replacement for silk, acrylic fibres were developed as replacements for wool (as I type this I am wearing an acrylic jumper) and PVC is sometimes used in clothing as an alternative for leather.
However vegans who consider themselves to be ecologists might face a certain dilemma in using modern materials which are by-products of industrial processes. By the same token, some ecologists (including possibly some dietary vegetarians) might argue that animals and their products are natural renewable resources which humans have exploited since the year dot and should continue to do so. The fur industry has been using this argument, particularly in relation to the lifestyles of the indigenous (First Nations) peoples of Canada, with whom the first European colonists traded.
Although there is a very good ecological argument for a vegan diet in terms of the volume of food that can be sourced from the same area of land, one needs to be wary that there are also ecological arguments that can be used against veganism (ie in favour of exploiting animals for their skins and/or their labour). I am not going to back up the latter arguments, but I think that it is important that vegans do not succumb to the backward-looking world view held by most in the ‘green’ movement, who are possessed of a ridiculously romanticised vision of pre-industrial society.
To me the vegan ethos, veganism, the vegan movement, as it were, is a forward-looking world view. We don’t need to exploit animals as our forebears would have needed to, so there is no excuse for doing so. There are environmental compromises in every form of clothing or transport in terms of the source materials and production and we just have to live with them. It doesn’t trouble my conscience wearing a material which is a by-product of the petrochemical industry or my driving a petrol-fuelled car. I am comfortable with technological advance and I don’t want a pre-industrial standard of living.