Are the stickers on the Hella 550 driving lights acting like a Bulb sheild or preventing glare, or is it all for looks?

For looks, I'd think. Any light produced by DRIVING lights s/b considered useful light, since they would/should only be used when there's no oncoming traffic. Also, the same shell is used on the 550 fog lights that are already shielded, and the Hella XL lights that have heavily shielded bulbs, yet those logo stickers are also on those lights, where they'd serve no glare-reducing purpose.

There is no useful light that is emitted from the very center of the lamp lens. That is why on many headlamps, the center of the lens is used for logos that are molded into the lens or stuck or lasered. It is only styling needs that makes the center of the lens be free of any markings. In fact, if it weren't for ECE and US regulations, vehicle stylists would have no markings on any lamp, for the purity of the look. On the other hand, just look at alloy wheels; they are usually molded with lots of information, none of which is required!