Why? For starters, you child will love it! Seeing my 5 year old's smile when she saw me waiting for her at lunch was priceless! Second, you get to talk to your child at school and have her tell you how lunch works and what happens. Third, you get to see the kid next to you covered in pudding. Seriously, the kid sitting on my other side had pudding EVERYWHERE! Apparently his pudding container exploded in his lunch bag and was all over, and as he was taking things out, he just continued to spread it on everything he touched. LOL!
Most of all, though, it's a great bonding experience as your child gets to show off his/her mommy/daddy. My 5 year old was so excited to tell everyone that I was her daddy!