Disadvantages of Stare Decisis
Over-subtlety or Artificiality
However a judge is forced, but it were follow an earlier case that, his conscience may preclude him from following, he might be inclined for 'distinguish' the present case from the earlier case. Thus this artificial 'distinguishing' sometimes creates artificial differences that make case law over-subtle for such.
Bulk and Complexity
Conversely so many cases are being decided everyday through courts all over the country, case law has become bulky and complex and it is suspicious if judges would really know whether a relevant earlier case had been decided to sure about, say some ten years ago.
Hence rules of law are made in complete bits and pieces.