I have worked in the corporate world for 30 years and it makes me laugh when people have the assumption that changes to the way a large corporation interfaces with its clients must be well thought out, as so much money is available to throw at it.   As you say, software developers move from company to company.  Their programming is only as good as the information they are given by the management of the individual companies.  That is where the problem lies.  Most managers these days do not know how their company works on a day to day basis, and they rarely seek input from those that do, before commissioning changes.   They, like the software developers, move from company to company in search of more lucrative contracts.  These days they rarely work their way up from the shop floor.  The bigger the company, the more distanced the management are from their customer base, and therefore the less likely things are to go smoothly. 

Here is an example from when I worked in an insurance company.  A software update was brought in to save money (i.e. cut staff from a specific department although that wasn't how it was pitched of course!) and the whole company had to attend meetings to show how wonderful it would be.  When my team attended the meeting, we noticed that a function that we used on a day to day basis had been removed.  When we highlighted this, we were told "Oh we didn't think anyone used that any more".  Well, if you'd asked us we'd have told you.  After a few days they provided us with a 'work around'.  (Oh how corporations love that phrase!).  The trouble was the work around meant a task which took minutes, now took hours as it involved manual processes and phone calls to clients.  Never mind, the senior management got a pat on the back from shareholders because the goal was to get rid of staff in a specific team (not ours).   They were able to use this example of money saved to get them better paid positions in other companies which they did within a few months.  In the mean time, my department had to fight to get extra staff to do the job which used to be quick and easy.  By the time some of the staff who had been made redundant were rehired to work on my team, the management had already left for lucrative pastures new. 

That's the corporate world, folks.  They really couldn't organise a pass up in a brewery (intentional typo of course!)