With 100 serious and less serious bugs to fix and interesting suggestions to improve the game that I think was the least important characteristic to introduce. An option to switch it off is necessary.
There is now an option on your settings page to show the aircraft list by default. You can even fully restore the original functionality by using that option and setting your filter to 'all'.
That said, I don't think performance and efficiency is remotely the "least important characteristic" to work on. Several crucial pages do not scale well and become extremely slow to load, and on top of that, most of the computation is wasted. This change targets several pain points large airlines face on a daily basis:
1) Loading the list of target aircraft when trying to move routes (and then being inundated with a gigantic, unwieldy list that mostly goes unused and is a complete waste of server resources). During peak periods, restricting the scope of that list makes the difference between being able to replace aircraft or not.
2) Likewise, generating all eligible aircraft for the "Add Flights" tab whenever the route details page is opened is extremely inefficient. If your airline has more than 1,000 aircraft, that list is hard to navigate, slow to load, and a waste of server resources, especially since a large proportion of time you're not even adding flights. That mandatory overhead just doesn't make sense from any perspective.
These two changes will avoid a lot of unnecessary work done by the server, thereby improving performance for all players regardless of airline size. From the volume performance-related complaints raised daily, many players would agree that it is in fact a major area of the game needing improvement.