Scouting and dogfights was a lot of what airplanes did in WWI, plus a little bit of bombing and some strafing. However, the importance of these two roles should not be underestimated. Reconnaissance is one of the most important aspects of warfare. If you know where the enemy is but the enemy doesn't know where you are, you have so much more room for activity. You can march around him, you can attack where he's deployed his weakest troops, you can bypass defenses, and overall, he's fighting with his pants down. In the modern era, reconnaissance also includes artillery spotting, which made airplanes part of the most deadly weapon system of the era. This should not be discounted.

On the other hand, dogfights are a form of counter-intelligence. If the enemy has his hands full with the hail of bullets you're sending his way, he is having significant trouble observing the goings-on down below and providing adequate information. You're also shutting off the visual feed (so to speak) to his artillery, making his most-effective-weapon-system less effective. A prime example of this was in Fokker Scourge in late 1915 early 1916. The Germans adopted a synchronization gear system which allowed machine guns to be fitted behind the propeller in line with the pilot's field of view, offering much better accuracy in dogfights. As a result, the initial German offensive at Verdun was prepared with minimal French knowledge, and the initial days of the offensive caught the French on the backfoot. The 11 month battle which consumed a million Allied soldiers went off to a very bad start because the Germans had good aerial cover.

The airplanes of the day also engaged in strafing. While this was not a particularly efficient way to kill your enemy, it had a critical importance. When the skies above you is raining death in the form of hot lead, it tends to make the situation a significant emotional event for the soldiers on the ground. This makes it harder for them to advance, or man the machine guns that is chewing up your own guys. It forces them to look in two different directions and direct their weapons similarly.

Airplanes were a new machine, but they were definitely dead useful. By a few months into the war most commanders have realized, which is why so much effort was dedicated to the air corps in every country during the War and all through the 20th century.