Front lens caps typically come in two categories: The pinch side type, and the pinch centre type:
The left cap is the slimmer, and came with one of the pancake lenses. The right cap is the pinch centre type, which I prefer.
The reason is that it is easier to remove and insert when you have a hood mounted, as illustrated with the Lumix X 45-175mm lens:
In this case, inside the hood, the slimmer pinch side type cap would be impossible to remove when you want to take pictures.
However, I often find that the pinch centre type hood grips are a bit slippery still. Especially in cold weather, it can be hard to get a grip on the levers that loosen the hood. To improve the usability, I tend to glue some small plastic parts on them, to increase the friction. Here is an example:
I took the yellow plastic parts from the locking ring of a soda bottle cap, however, any plastic part that has some texture can be used. Adding these strips of plastic makes it easier to feel where to grip the cap, and easier to hold it. The yellow colour also makes it quicker to spot the grips in dim light.
Why the manufacturers don't add some grip surfaces on the lens caps is beyond me: That would surely improve the ergonomics out of the box.