If you move into a space seen by an enemys piece they will be able to attack you on their turn. This is no different for destroying a piece, the enemy can now see you, and will attack on their turn. Why would shields protect you from one easy to see scenario and not the harder to see one? It's hard to blame the player for being oblivious to something they didn't know about, even if it was a "learning experience" for them. All that "game mechanic" causes is needless frustration.
Seeing the consequences of your moves is a part of chess that's true, but this game is already different with shields protecting you from being careless.
I find a valid way to lose is not looking for a synergy in your pre-round upgrade choices, being forced into a situation where you have to take risks and failing to be lucky. But all situations where shields apply are ones where you are careless, and not being careless, again as indicated by the shields , is not part of being skilled.
The mechanic would not be hard to implement either. Just assume the piece you attacked is gone and check for enemy line of sight.