This may not be a popular opinion, but I simply do not understand why you need the massive environmental and economic overhead of creating such "alternative meat" products if you want to avoid eating animals. Plants are eatable and tasty without processing them into fake meat first.
Possibly a slight generalisation, but these would mostly be aimed at people who eat processed food anyway, not those who cook. That is, the market isn't current vegetarians/vegans; it's people who eat processed meat.
That said, I'm not sure how bad the environmental overhead is. The main source of protein in these things is often either soya or peas. Soya is a bit of a tossup depending on where it's grown; it can be either very good or very bad (though probably still less bad than meat). Peas are generally pretty low overhead; in particular, they're nitrogen fixing (as are soybeans), so need less fertiliser.
Most of these new products that you see advertised are not aimed at Vegetarians or Vegans, but are actually aimed at meat eaters. Tesco has a range of meat products (such as burgers and mince) that are actually a mixture of real meat and plant based meat.
A lot of people know that meat has a high environmental footprint, and people are becoming aware of how poorly animals can be treated by factory farming.
Those people are looking to reduce their meat consumption, and these products are a crutch to allow that to happen.
