Being a parent who has taken my daughter for Mani and Pedi since she was 2 I really don't see a problem with it. It is mommy and daughter time. My daughter is also allowed to wear lip gloss. I would say that she never wears it outside of the house but she does but usually all around her lips... Really is lovely.

She really isn't all that into the lip gloss anymore and when she does put it on she doesn't put much on compared to how she used to.
As for other makeup... We don't allow it but we have had a few cases where we have made exceptions. IE. B-day party for princess dress up and the older girls put some make up on them and ballet for performances.
Does this make my child want the makeup more? Absolutely not. In fact, she hardly asks for anything now. I haven't taken her to have her nails done in at least 9 months but have painted them myself a few times. Have I robbed her of her childhood? Hahaha the child who is full of imagination and creativity .... No.
I understand that every parent has their own style and I would never attempt to push any parent into allowing their child makeup or nail polish and I must admit I was shocked they included makeup at a party.... I certainly wouldn't BUT in the same fashion please don't jump to conclusions on your end.