in reply to de-inventing the wheel (discussion)
Good, alterable code is living code. Any code that a company is afraid to change is dead code. If programmers refuse to upgrade because they fear breaking code, then think of how hard it will be to change that code to add a feature when a customer needs it. On the other hand, if the code is strong enough to withstand a few upgrades, it's a good sign that it's pretty robust code.
If code has a good set of regression tests behind it, then upgrading is easy-- just do the upgrade and run the tests, and you can have confidence that you haven't broken anything major. Most companies don't encourage writing automated regression tests, just as most companies don't encourage writing living, flexible code.
On the other hand, companies will argue that they're in the business of making money, that they don't pay programmers to introduce bugs into already-running code but to add new features instead. There is some justice to this position, and one must make reasoned choices as to how much time and effort one is willing to expend to keep code high-quality. However, I feel that such reasoning is overapplied. In the long term, good, robust, upgradeable code saves a company far more time and money than any number of short-term cost savings.
The sad truth is, though, that many companies right now are going for short-term gains because they don't expect to be around long enough to HAVE a long term. So I have some sympathy for the devil in this case, although I'm not quite his/her advocate.