Comrade Thirith, I'm in the same boat as you. In my younger days, in Takistan, I could spot a TK regular from across a valley and plink him with my trusty AK. However, it's not the same on Altis. I struggle to spot distant targets with the 'naked' eye, and the distance at which sharpshooting is effective has come down appreciably. Which I think is fine.
Quite a few of the mechanics in Arma 3 are about slowing the pace. In Arma 2 we could jog up a mounting, insta-spot some TK troops in the next valley and lay down punishing fire before making a pot of tea. Now, in Arma 3, we're really rewarded for managing stamina, using observation positions, and taking time to use the binos and rangefinders. When it comes to actually dropping the enemy, we're rewarded for closing with the enemy, or coordinating larger volleys.
In other words, I think it's useful to try and park your Arma 2 experience and take a fresh look at your personal and element-level tactics for Arma 3. My experience has been that once you adapt, Arma 3 has challenges and pleasures all of its own. Hope that helps!
