As I see it
In the 90/00s we in IT were seen as a cost, an unnecessary budget burden and in many ways we were. We had poor products that didn't scale across very large organisations. Through as series of acquisitions and mergers many IT systems were brought under one roof and we had the whole "Legacy systems" issue and systems not talking to each other. One by one, bright sparks decided to "buy a new IT system" and various IT companies made a lot of money without delivering a system that the people who create revenue for the companies could actually use.
We were then seen as an even more expensive department that was delivering even less products. Along came the raft of outsourcing and the opportunity to listen to the salesmen and slash budgets, the link between business and IT was further broken.
Next we hit the massive growth in consumer IT, suddenly people not only expected corporate IT to work as well as their mini network at home did but also give them the same flexibility as their home network, despite home and corporate being two different beasts.
IT still have poor products to work with and on reduced budgets. Roll out 8000s machines, with different application portfolios, different access rights, hot desking, legacy systems, security, lack of management buy-in, dumb decisions, crazy policies.....
We are still delivering poor products as our goalposts change with each management whim, we want flexibility, security, availability, redundancy and we want it cheap. Now we're into cloud, BYOD and I want my iPad to print to that printer and use it as a full on workstation.
As IT we need to align with our users to deliver services that they need. When we are seen as delivering value we will stop being seen as a cost and barriers to change.