I've got the smallest digital full frame (the Sony RX1). Compared with your linked analog Ricoh GR1v, the Sony is bigger because of its much more capable lens. Putting the Ricoh lens on the Sony would have limited the quality a lot. It's a question of "do the elements fit together?".
The sony lens is so big because its a lot faster. Sony also makes a pretty compact 35mm F2.8 lens comparable to what you could fit on a point and shoot. The elements definitely do 'fit together'.
