Former SAP employee here, who btw, is
very critical of SAP. I also happen to have worked in Escalation Management at SAP, who's prime responsibility was to take SAP projects that were about to go south and put them into "escalation" before they the hit newspapers.
Let me try to explain the mystery around SAP.
1. Most of the situations where SAP projects go haywire is largely due to (a) incorrect implementation by the service integrator and (b) challenges between business processes and systems support for those business processes. Sally in accounting wants to see sales per unit for the Germany promotional rollout, while Karen in marketing wants to see overall sales for 100 store locations in both Germany and Netherlands. The NL's retail stores don't split out VAT because their POS systems don't allow you to do that...etc etc. You can see where this is going...
2. Implementing ERP at the global level is incredibly complex. There's this idea (especially in the HN circles) to just "throw SaaS" at the problem, but it's not that simple. If you haven't been involved with an implementation at this size, it's not worth discussing. It's a wonderful hodgepodge of culture challenges, project management methodology clashes, and misalignment of strategy.
3. Yes, no one ever got fired for hiring SAP, just like they did with IBM. This is obviously changing, but still has some truth to it (see next point).
4. Honestly, being a CIO of a global F500 company absolutely sucks. If you try to stick your head out and do anything innovative and it fails, your axed. Many CIOs simply go into turtle mode - protect the budget you're given by the CFO and just don't f anything up. A CIO who choses to build a custom ERP and fails will be fired 100x faster than one who uses a packaged solution and it fails.
5. What's the alternative? Oracle? At this level, they're all the same (ok, not totally true, but generally accurate).
Happy to answer any questions...this area is unfortunately/fortunately close to my heart.