You won't have nearly as many frames to repair if you start gluing them together. They don't split out and fail like frames held only by a nail. The nail is a wedge in the wood carrying a load. It creates the split. When you glue, the load is distributed over the joint area. Also, you don't get racking of the frame which further stresses the joint and causes splitting. If you get a weak spot, it can be reinforced with a glued on splint in most cases without dissassembling the frame. The only time I've had to do that was a topbar with an area of short grain that broke.