After several hours of gameplay on sandbox and testing my creativity, I decided to get more serious and start a new career mode. As an airplane lover I really felt a lack of utility on creating atmospheric aircrafts despite being useful on running short distances to gather surface samples on the very beggining of your career. I really saw no need on building those gigantic and awesome airplanes. It would be even more awesome building those on career mode, where you would to plan and desing a even more efficient and better airplane then your casual "sandbox jumbo". As a simple solution, I came up with the following idea:
Add "Airports" around the surface of Kerbin capable of picking up or delivering Kerbals. It doesnt have to be too complex, just a runway and a "terminal".Beyond the missons you receive form the Space center, you would have some "passanger kerbals"(as a new type of kerbal, like the Pilots, Engineers and Scientists, and now, Passanger) on standby. Each kerbal would have a unique destination, and taking him to the "airport" that he wants to go, would reward you with money. Further away the airport, more money you get.
That would encourage the player to build a better, saffer, more efficient airplane and as a whole, creating an extra purpouse for atmospheric aircrafts.
To make the Kerbal passanger transport make sense as a whole, it would be a cool thing if we added something more beyond taking those random kerbals around Kerbin. It would make more sense if those airport were added next to a cluster of KerbNet Antennas in order to, in theory, keep the maintaince of those antennas. Also, there would have some bigger airports, which those, would be larger and contain a science only building in it, so having more kerbals in it, would increase the income of science. Taking scientists to an airport, would increase the amount of science income, and taking engineers, would increase the efficiency of the antennas.
Conclusion to "Canon(?)":
Beyond transporting Kerbal passangers that would give you money for that, you would have the option to take Scientists and Engineers too. Taking scientists to an airport, would increase the amount of science income, and taking engineers, would increase the efficiency of the antennas near that airport.