Shields suck. That's why. Admittedly, shields suck less than two HP, horse whistling or negligible bonus speed.
Shields are awesome when paired with a 1 hander, especially with recentish weight reductions. The reduced risk in a group allows for some tactics that will get you killed without the shield
Be a pest by turtling. You can split enemy groups or get behind them a bit so they focus you and move off your weaker team mates.
Draw people towards team mates when they tunnel vision on the shield
Block for teammates (ranged or melee) or just stand in the melee waiting for an opportunity without much risk
Probably have the best choice of nudges in the game.
Towards the end of the round you typically have lower health and will die to ranged without a shield. You can usually find one lying around and 4 skill points should allow you to pick up most shields
I don't do it myself, but a light shield with some armour will reduce the damage you take in the back when you put it there
Doing that changes your role though, and as a 2 hander that stuff isn't really your role in the game. Clutching at the end might be easier though with the shield. Or 8PS with low WPF might still be alright if you fancy trying another role