Additional questions help you understand the causes and reasons behind your customer experiences. You can therefore implement solutions faster, which would be impossible if you tracked only satisfaction.
Ask your customers to share their emotions directly when they experience it in your point of sale. Combine it with additional question such as Socio-Demographic question (age, gender, revenues, ...), Repurchase Intent or Brand Equity and improve their willingness to purchase from you.
Sources: Christian Homburg, Nicole Koschate, and Wayne D Hoyer. Do satisfied customers really pay more? Journal of Marketing, 69(2):84–96, 2005.