When did "tactical" become a dirty word?
As I have discussed previously on this blog. There are actually several reasons why most BI initiatives are departmental, often using different tools. It is not that the business people are a crowd of masochists. The first reason is that a lot of BI needs are legitimately local in nature, specific to a department or operating unit. It is dramatically easier for a department to set up a data mart that has just its own data, and stick on top of that a reporting tool like Business Objects or Cognos, than it is to wait for the IT department to build an enterprise warehouse, which takes 16 months on average to do, costs 72% of its build costs every year to support, and then usually struggles to keep up with changing business requirements.
So it is not a matter of "accepting the significant advantages" of an enterprise approach. Everyone accepts that such an approach would be preferable, but the IT industry has made it very, very difficult to actually deliver in this promise, and people naturally fall back on "tactical" (i.e. working) solutions when grandiose ones fail. Ideally you would like an enterprise data warehouse, deployed in a few months, that can deal with business change instantly, and can at the same time both take an enterprise view and respect local departmental business definitions and needs, which will differ from those of central office. The trouble is, most companies are not deploying data warehouses like this, but are still stuck in a "build" timewarp, despite the existence of multiple packaged data warehouses which can be deployed more rapidly, and in at least one case can deal with change properly. Until this mindset changes, get used to a world with plenty of "tactical" solutions.