At the moment the Sword and Shield style is not very good, and I can't find any posts requesting an improvement. It provides +2/+4 AC bonuses against missile weapons when using a shield. In effect, you only actually get solid benefit from it when you're fighting missile-armed enemies who you cannot engage in melee combat. Very few of the tougher fights in either game involve archers. I can see it being useful early in BG1 when fighting bandits but this is all.
All other weapon styles (2h, 1h & dual-wield) have advantages in every combat you fight. If you use a 1-handed weapon and a shield you are usually better off putting proficiency points in a different melee weapon or dual-wield than putting points in Sword & Shield style. Look at it this way, 2 points in both longswords and sword and shield style is less versatile than 2 points in longswords and warhammers and the only downside is less bonus AC vs. archers.
I would suggest changing the bonuses of Sword and Shield style from +2/+4 AC vs. missile weapons to +10%/+20% damage resistance when using a shield. This bonus is more universal and can be applied to just about every combat in the series. It synergises with Barbarian damage resists/Armor of Faith/Hardiness but cannot be abused until ToB when everything is easily abusable anyway. With this availability of damage resistance it may require a % resist cap, which is the main downside. As it stands a lot of gamers use Defender of Easthaven (+25% damage resist) in their offhand instead of a shield anyway - this proposed change would make shields more useful.