I too was disappointed that more was not made of the Alcock & Brown centenary.
To try to give a bit of perspective, I understand that there is only one curator responsible for Aviation and Space, and the museum is preparing to move its collections out of Blythe House in London to a new store at Wroughton in 2020. According to
https://group.sciencemuseum.org.uk/w...ew-2017-18.pdf "once complete, the facility will be home to more than 80% of the Group’s collection and will be accessible to the public through tours, school and research visits." Preparartion for the move will be very labour-intensive and may not need much spare energy for exhibition work.
I suspect also that the museum is nowadays focussing on cutting-edge science and technology, rather than technology that was leading the world decades ago. Perhaps aviation technology is seen as having reached something of a plateau, although there is scope for highlighting the ways in which the industry is striving to reduce its environmental impact, and perhaps other developments such as new fuels.