Its very cumbersome, that you can put and customize soldiers only in active squads:
This makes it just busywork. Because you have to constantly have to switch Squads for Soldier Customization and Equipment.
Better Option is to have a screen for all squads in where you can customize and upgrade Both Squads and Soldiers regardless of active Status. And you simply tick a box if you want a squad active or inactive.
With a line up of active squads shown at the left side like it allready is now. 
This would actually help this company to sell more weapons, better troops and so on.
Now, people buy just what they need because they know that changing squads and soldiers with gear is such a hassle.
If everything were easier to manage on the game menu, people would collect more to all squads and it would be so much easier to switch squads for the next round.
It would also encourage people to play longer on campaigns and by thus increase the amount that is “achievable” on the game without really doing anything special.