Would you like fries with that?

No you cannot eat in a fabric store.  Greasy fingers and textiles were never meant to mingle! Would you like an extra 0.7 meter of the fabric you are buying? I hear you cry out: wastage, too many scraps now and the cost, oh the cost....

Valid points of course but in my opinion I just love just a bit extra because....I get  extra options with this small extra piece of fabric.  If the fabric is of the stretch variety all I need to do is sew two side seams and a back seam with a split, sew a hem add  a bit of elastic and then I have a versatile outfit.  An easy way to increase the value of your purchase.  If the fabric is woven a waistband rather than elastic is basically all that is required.  Simple skirts can be worn with other pieces in your wardrobe.  Mix and Match possibilities.

Cost versus value.  Choice versus limitations.  

Sometimes a small extra cost allows a bit of creativity and a safety net if you make a blooper.

An example I will share with you...I finished a fully lined teal Vogue evening dress for a formal occasion.  The night before I pressed it and left a huge scorch mark on the back of the dress in a very noticeable spot-the bottom area.  I had extra fabric. I was able to unpick the panel and use the spare fabric. Crisis averted.