First off; when the team reaches the business targets; don't worry about it.
BUT
When I read the comments about working for years with Agile methodology I suspect that you are only partially implementing it. Without sprint planning, you are not using Agile.
This would be a good one to tackle on the retrospectives; as the process clearly would benefit from it. When planning is continuously on the low side: that's also something you should handle in the retrospective.