Any ERP Consultant knows.....
1) Big Bang ERP Deployment doesn't work, except on green field companies.
2) ERP is written for general and standard business procedures, and doesn't like being bent.
3) There is a massive cultural change required that need proper handling and training of the user population, companies are rarely, prepared to pay for it.
4) One size does not fit all, but we'll take your money anyway.
5) Consultants will deliver to contract, not to need, that way you can't be sued.
6) Best of breed is better, but more difficult to sell as it's more expensive.
7) We have shareholders too, why think we don't we eat our own dog food.