Why do clubs get increasingly upright as they get shorter?
Your swing plane is different for a wedge than for a 2-iron, and the shaft of the club is more upright for your wedge than it is for your long irons and woods. As the ball gets closer to you (which is the case when you address each club in the bag from your 2-iron to your wedge) the lie angle must change to accommodate the angle the sole makes with the ground. The clubs are designed so that if the sole from toe to heel is horizontal at impact then the face is pointing to the target. If the lie angle is too upright, even good shots tend to go left. If the lie angle is too flat, they’ll go right. This is why the proper lie angle is critical.
For putters, the lie angle for most golfers should be approximately 72 degrees assuming the putter is properly fitted. For more on putter fitting, see Chapter 2 of The Fundamentals of Putting.
Hope this helps.