If I recall, I think Rick came up with the actual angle of 7 1/2, but I may be drastically wrong on that one. 7 works for me. Mostly because most of my instruments have pickups, and there was an article written on it years ago, I think it was for Fishman, but I install Baggs. The angle allows very nice compression on the UST, without any tilt. That would be THE reason why I do it. As Paul Okami described a pickup installation I did when he was over - very uneventful.
However, once intonation is set on an instrument without a UST, if it ever came back for one, taking material off the bottom is all it takes. If the action needed to be lowered in the future (like if higher tension strings were installed), lowering the saddle also shortens the scale length at the same time - basically, the top of the saddle doesn't need to be touched.
Break angle remains basically consistent, but because all of mine are low G, the line is closer to the neck on the 1st, and closer to the tail on the 4th. Note: Because of the angle, the neck side of the saddle is cut much steeper than normal, and the back is cut much shallower. MGM posted an image years ago of one of my saddles, but I'm not sure where it went. Again, I didn't create this, I just copied what Rick created.