The reason single action grip frames are made to roll in the hand is to make it easier to recock the gun with just the hand holding it. Your other hand was assumed to be busy with something else, like the reins, or a saber....
Today, that is rarely the case. When you get to shooting 200gr+ bullets at 1200fps or more, the regular wood grips can be painful. Grips that fill in behind the triggerguard help A LOT, and I find the rubber Pachmyrs to be much more comfortable for heavier loads, and not any hinderance with lighter ones.
The look upsets the purists/snobs, but its not their gun, its MINE. And the oversize rubber makes it better and easier for me to shoot. The guns still roll in your hand, just not as much. I'm much happier when the muzzle only rises to about 70 degrees than 110 degrees, and not having the triggerguard rap my middle finger.
Everybody's different about what they like and what they feel, so do what works for you, and I'll do the same for me.
Plus, I don't need to wear gloves....