I think it would be great if there were more land blocks available for purchase. The size of everything required to support the large aircraft (deicing pads, parking pads, terminals) takes up so much space that you quickly outgrow the current four blocks. This is especially true if you want to support a lot of large pads. You essentially need to sacrifice small aircraft entirely at some point.
Might even be able to add it as a project that can be researched 4-6 more times: “Negotiate additional land” and make it take a really long time and/or make it really expensive.
If more land was available, we might be able to make the landing light strips more realistic and make it impossible to build taxiways through them.