It's because of their "Hotel California" strategy: you can check in but you can't check out.
Seriously, once your company is using SAP, it's rarely going to be worth rejecting them. It will be more cost effective to just pull SAP data out of SAP and use it in whatever way you need to than it is to try to customize SAP or get a new system that better fits your needs.
A big reason they stick around is because decision-makers are so fearful of changing very basic systems (i.e. payroll, accounting, etc).
Seriously, once your company is using SAP, it's rarely going to be worth rejecting them. It will be more cost effective to just pull SAP data out of SAP and use it in whatever way you need to than it is to try to customize SAP or get a new system that better fits your needs.
A big reason they stick around is because decision-makers are so fearful of changing very basic systems (i.e. payroll, accounting, etc).