A customer manually writes every dimension they have on the drafting file into an excel file and they want to know if there's a way to do it directly from NX
Without API code: Not easily.
With API code this can be done.
I would suggest the customer check out BCT Inspector (Siemens partner)
Production: NX10.0.3.5 MP16/TC11.2
I'd rather be e-steamed than e-diseaseled
Here is a link to a proof-of-concept journal that exports dimensions to Excel. It only exports the main dimension text (no tolerance or appended text) and isn't super robust (doesn't do much error checking and probably won't handle hole callouts well), but it is a start.
There is no easy way to export all dimensions from a drawing to a spreadsheet, but there IS an easy way to do this with PMI. Just use the PMI Report command. This likely won't help your customer now, but may give them a reason to consider investigating and using PMI for their documention needs in the future. And you can create a drawing with PMI too.