The tight glue line is about having both surfaces be flat, and mate up togethers perfectly. Use a straight edge and stand it upon the surface and look at the light coming from under. Once a straight edge will lay flat across both, they'll glue up tight.
The angled taper I think is for aesthetics, and I think started w/ boo backed bows where typically one fades the boo off at the end. I think it looks cool and will be as sound as any other approach. That last two inches of limb should not ever bend anyway, and the glue should hold easily.