@hunterdouglas
You make some good suggestions. But.... not sure there is much we can do to satisfy these requests.
A fleet of GA aircraft 'in a box' (as we did with the old PlusPaks) is feasible. However, standards are a LOT higher than in PlusPak days and, because there are a lot of freeware AI aircraft about, I am not sure we would be able to make much of a commercial success of this one - certainly not enough to justify costs even without liveries. More importantly, any such pack would need to function 'in game', rather than just provide aircraft. We'd need it to work (and be bought by) a decent number of ordinary users - not just DIYers (see below).
Creating an airport modifying tool is not something we'd really want to get into. It's not our bag and we generally leave tools development to third party devs (see, for example, Real Taxiways from Black Square).
Over the (many) years we have been doing Traffic we have seen that buyers tend to fall into three categories:
Flyers - want a product that adds realistic commercial traffic to the sim so they are not flying in empty skies and don't see United Airlines 737s at Glasgow.
Spotters - like to watch the 'action' happening around airports. We even built a 'Spotty' tool to satisfy this need in a previous incarnation. Suffice to say we haven't included Spotty in any subsequent version.
Tinkerers - people who like to repaint aircraft, add missing planes and schedules or create flight plans from the past or in more obsure locations.
The vast majority of buyers of FS200X/FSX/P3D/MSFS versions fall into the first category. We did find a higher number of Tinkerers for the X-Plane version, which is probably a function of the sim itself. X-Plane has encouraged tinkering for many years with things like Planemaker and flying on Mars. However, even 'over there' the majority of users still seem to be Flyers.
What this means, of course, is that we need the software to appeal to the majority of users and that's where a big chunk of the compromise comes in. It also means that any future developments and updates after initial release are usually restricted to more planes, new liveries and updated schedules. Beyond that, we are constrained by the commercial realities of dev cost vs sales potential.
So, while we dso our best to make it possible to modify and customise the Traffic offering, it's not a core part of the add-on.