Competitive edge for successful enterprise application vendors?

I had about twenty years experiences in IT and learnt something about SAP,Oracle E-Business Suite, OpenERP/Odoo, Compiere. I studied their histories and features with their competitors. From technology point of view, I think UI abstraction is their most important competitive advantage:

What's your opinion?

UI abstraction: good form/presentation layer with or without minimal logics. They can easily come up with a new form presentor when a new UI become mainstream. However their competitors have struggled to modify their system module by modules, lagged behind, and eventually out of business. UI history: TUI, Win32/x-windows, WinForm,WPF, Flash, Web, VR...

SAP: SAPGui Oracle E-Business Suite: Oracle Form OpenERP/Odoo: View xml Compiere/Adempiere/Idempiere: Application Data Dictionary