IaaS has become much much more than just compute on demand with an API and pay per use. Interesting to note that Oracle cloud announced to match AWS IaaS prices for their customers which is a cool and bold move. Obviously this will help to keep Oracle customers on the Oracle cloud.
AWS IaaS actually is more. You can have cheap reserved instances and even cheaper spot instances. Today AWS announced spot instances with a block duration for jobs that need to be finished but run economically. Good to see that competition keeps bringing new features. Remember when many years ago I wrote about the benefits for customers that will be caused by cloud computing? Nowadays this has become a fact.
There are more public cloud advantages and features you should know.