Legacy systems and current infrastructure - Information System
This problem is most easily understood using the everyday example of the rail ways where the rail network infrastructure is so large and well established that any new innovation must be used in conjunction with infrastructure that may be over a century old. It is therefore difficult to introduce a new type of train as it has to interface with a track that maybe a century old meaning that the ability to use new technology is limited at conception. The rapidly changing face of technology especially in the area of information systems and the race to install these that has been taking place over the last 40 years results in many cases (especially in larger organisations) in solutions being chosen for their ability to interface and integrate with an older less able systems as the cost of an 'upgrade' or 'bolt-on' is seen as more palatable than a completely new system.
Hopefully however more recently with the trend towards standardised hardware and custom software; combined with greater vision being displayed by systems designers in terms of modular approaches; together with forwards and backwards compatibility strategies this problem should reduce.