That I'm afraid is your opinion. It's not mine, my opinion may differ from yours. It's why forums are fantastic because it's a place to debate different ideas. I don't mind been wrong, But If I give my opinion then it may wildly differ from yours. Please respect that.
Adjusting a hop mid game is something that should be automatic. You shouldn't even have to think about it for an AEG shooting white BB's. Been able to adapt and move that wheel to suit the ammo you have on the fly is an important part of the game. If you can't do it how will you cope when you rinse your mags in a long game and your team mate hands you one of their mags on different ammo. Or those times when a site simply doesn't sell 0.3's and you have to move to 0.25's.
I like to switch it about because I'm confident in watching where my shots are going. I'm not attempting to snipe, My guns are quiet enough that I can afford some time to adjust. I tend to engage at ranges that afford me time to do this. And I tend to have a team mate who isn't switching up offering suppressive fire to let me dial in. Likewise I may offer suppressive fire while they dial in.
At shorter ranges the hop doesn't have time to alter a shot significantly when switching about provided the ammo is close in weight, 0.2-0.25 or 0.25-0.3. You do the switch simply to beat soft cover. It's part of the tool box that is available mid skirmish, not to use it is to loose a key element that is available to you in game. Like everything it requires a little knowledge, and a little practice, And isn't a tool that everyone is going to use. The team I shoot with are pretty much all doing it because in the correct situation it offers an advantage on certain sites.