Consultants charge far too much and create their own work. They are employed to answer a lot of problems that can easily be solved using common sense or by using experienced contracting companies for free. They make a bid deal out of small problems to give themselves more work. They are often on a percentage fee basis so the higher the project value the more they get paid. Fixed price is better but still only as a last resort. They design overly complex systems where simple systems would suffice, just to get their fees up.
Consultants are employed far too often and unnecessarily.