My dear fellow, it has been this way many years!
Curry has been a favourite for years, in particular, l believe, chicken tikka masala?
When I worked in Sainsbury's in 1986, we sold frozen rabbit parts.
Haven't seen rabbit in supermarkets for decades.
The switch to convenience foods has been happening since the advent of fridges and, in particular, freezers. Since the 1960s we have been tempted by ready meals, quick, convenient alternatives to the traditional meal.
Since this time, wives have been liberated from the kitchen and have been going out to work and not been tied to the kitchen sink. The only proper main meal some families have these days is the Sunday roast but even then, they often go out for it to a pub.
As a nation, we are more adventurous food wise. That's not to say we have let go of our traditions. I'm very happy to cook everyone a roast chicken meal on a Sunday with stuffing in the style my Gran used to do it (made into balls, flattened and fried in butter) and Yorkshire and gravy, and all my lads absolutely love it!