Just to be fair there are 737s with fail operational autopilots capable of 25 knot crosswinds. However as this incident demonstrates and we all seem to agree the autoland system is not ideal for this kind of situation. Its misuse and also misunderstanding the fuel situation suggest the crew were out of their depth.
The Boeing flight crew training manual provides a guideline that up to 40 knots steady crosswind for manual landing is allowable subject to company limits. The guidance on gusts is slightly less clear. They do not change the limits but make things more difficult. So basically it is up to your own judgement regarding the gusts and indeed your own experience and state of health, tiredness etc.