Two points about Syndicate's "Breaching" system (they don't call it hacking):
1. There are a few moments where, if you bothered getting used to using the system, it made some fights a LOT easier, and was a MUCH more efficient and rewarding way to win the fight. Problem was that the level design and enemy placement did FAR too little to encourage this kind of behaviour.
2. Co-Op. I know Yahtzee almost entirely sticks to single player in games, but if you're in Syndicate's Co-Op mode, you have a MUCH wider variety of Breach applications, and you have to choose only 2 that you can bring into each mission with you. There are some which could use tweaking, because even at their basic level they're unbalanced (C2C Pulse, Virus, Battery), but it's not such a huge problem with Co-Op. Also, the maps in Co-Op are MUCH better designed for abuse of the Breach mechanics, allowing players all manner of interesting "app combos" where players coordinate their app use WHILE shooting to screw the enemies over in increasingly efficient ways.
Even without using any other abilities, players can heal one another. If you have 2 players with a good selection of apps between them, you can coordinate with one another to seriously tear apart the enemies. Popping a well-timed Virus on an enemy Agent or a guy with Reactive Armour, or breaching a Liquid then using Backfire to knock him down and make him more vulnerable to fire, then combining it with Damage Link so you do even more damage.
Also, in Co-Op, most mini-bosses require you to breach before you can do damage (either a Virus app or a standard breach to take their armour down), and while some enemies are resistant to a few apps, Virus works on everything, and Backfire works on everything except Agents.
In single player, breaching is MOSTLY a gimmick, but there are moments where it shows that with proper design, it COULD have been more. In Co-Op, it's a core gameplay feature and not a gimmick at all.