These kind of minor applications are just adding minor bits and sticking plasters. Edinburgh really needs a wholesale rebuild to cope with passenger numbers it now has, but I can't see it happening.
A lot of it comes down to two things.
First cost and return on investment. The owners obviously want the greatest return for the lowest investment.
The second is that airports realise sticking plaster developments are likely to be approved without too many issues. Major rebuilds, on the other hand, will likely see many years spent in the courts and fighting against various groups/ government bodies which means many £££.
I'm a firm believer that national infrastructure projects planning/ permission should be taken out of the hands of local councils and put in the hands of a national pro-growth body with a limit of one judicial review in total on any project.
Bristol Airport's local council, for example, is determined to limit growth at the airport and, as a result, the economic development of the South West and South Wales. Why should one small authority have power over such a large area and why should there be such a massive democratic deficit?
I'd be interested to know if @pug1, @TravelDream and @Skymonster currently live in the vicinity of an airport. It's all well and good pontificating about the benefits to the country as a whole when you're not personally affected.
I grew up with a rail line at the end of the garden. Trains passing are fundamentally quite noisy, but you get used to it.
When the frequency of the trains increased (especially as there used to be basically no Sunday service), my parents were the first to complain. But as I said before, they chose to buy a house with a rail line at the end of the garden.
A line with one train an hour today could easily have multiple per hour tomorrow.
Heathrow has been there a very long time. Before 99.99%+++ of residents affected.