Software abstraction, or software frameworks for that matter, does not make an architecture complex. The system or the application that we are building is that which is complex and therefore we need to abstract certain aspects of it in order to minimize, or even at least manage, its complexity. Abstraction keeps the developers zero-in to the business codes rather than concern itself with say audit trail, logging, rendering of pages, handling different protocols, transaction, etc.

A multi-layered architecture is not necessarily cumbersome and slow. On the contrary, if implemented well, it improves the quality, readability and reusability of codes because they isolate system or application processes.

Snoobab,
Yup, you're right that fitness for business purpose is the primary concern. The point I was trying to make was that huge and cumbersome abstract frameworks often slow down the application with unnecessary layers. However, the larger category goal that speed and others fall under is one of "fitness for business purpose - does it benefit the user do their job". Things just have to be fast enough to do the job and no more, and there is the other peril developers can fall under which is they optimize it to death at the expense of having a clearly architected system. Thanks for picking me up on the point.
JoeW

Umm speed should not be the primary concern, an effective and clear business fulfilling model fit for human developers is though. Code is written to be read by developers and a great simple consistent model that obviosuly fulfills business needs should be the primary goal.