[rossdavidh]

If you don't, basically, change your organization to the way SAP (or any such "product") already is set up to run, you are essentially buying a programming language (or perhaps framework) that is poorly documented, with a much smaller online community (for examples, tutorials, Stack Overflow questions, etc.). So it is the same problem you already don't like your solution to, except with a lot of things stacked against you now.

But, they won't make the sale if they honestly say "use it the way it is or else don't buy it", so they say something more along the lines of "you can customize it".