Exploration- Nothing is stopping you from exploring if you want to, it is not like it is being forced on you. Also it won't affect new players/characters since you have to go through the MSQ and finish the MSQ "The Ultimate Weapon" as one of the requirements so they will still have to go through ARR on the ground. It is not like new players will start out with flying.
Reduces number of travelers on the land route (Socializing)- I mean I don't really see that many people on the land routes and how many people stop and chat? I am sure it's not a huge number. Again nothing stopping you from using the land routes and talking to the new players/characters that are running around the land.
the flight system prioritizes A to B travel and ease of movement in an objective based system (no adventure, over trivializes aspects of travel example: bofuri ep 7 angel mode quest- If adventure is important to someone they can still use the land route and go explore and have an adventure, again this doesn't affect new players etc since you have to go through the ARR MSQ to unlock.