The list of complications from intubation are a lot longer than that...many of which cannot be treated by an EMT-I. You need not only the ability to stick a tube down the trachea, but also to cope with (hopefully all) of the possible/probable complications. Pneumothorax, bronchial and esophogeal intubations, lacerations of any of the soft bits between the mouth and lungs, brocnchospasm, inflammatory responses, vagal stimulation can cause all kinds of havoc depending on the pt, etc. etc.
I know how to intubate a dummy...the acual process of passing the tube is not so hard to teach in principle. Thats the part that seems easy. Now add to it very detailed knowledge of the anatomy and physiology of the upper airways, the innervation of those areas adn various reflexes that occur when you jam plastic down someone's throat, the multiple controlled clinical exposures needed to become proficcent, the various techniques needed to cope with people whose physiology is different from recussi-annie, and once you do that, you get to get into the physiology of respiration and ventilation, etc. Actually it wouldnt be so bad if all this was covered in all the EMT courses, but the amount of time required to acutally teach all that, with the necissary background, is a bit more than the current time requirements.
The complications from IV's are relitavely more benign. Certianly non-existant, but generaly not so bad.