[kasey_junk]

Extensibility is important in some cases and a detriment in others. Most of the rules about extensibility came from environments where the code was running in many places at the same time (ie delivered to customers).

In a SaaS environment the code needn't be extensible as there is only 1 copy of it. It is much more important for the code to be changeable, rather than extensible and in many cases the things you do to make code extensible make it harder to alter fundamentally.

Its important to understand that how you deliver your software is one of the biggest guiding factors in how you design your software and take that into account.