"No Boxed Gifts" makes a lot of sense if the wedding (or the reception) is being held in a different city/country from where the bride and the groom will ultimately settle down. So they don't have to transport a bunch of big boxes (likely full of lame and recycled gifts).
But I am not sure if giving gift vouchers to people to have a meal is a good idea. I won't do it. The purpose of wedding reception is to celebrate a milestone WITH your friends and family. Its the occasion, the ambiance, an opportunity to meet old friends and family, and best of all, be part of a group dua for the newly wedded couple.
Most people can eat out any time they want. The guests are not likely to be so poor that they'd be ecstatic on receiving a free lunch voucher. This kinda defeats the whole point.
If the bride/groom (their family) wants to save money, then don't invite a ton of acquintences you don't really want to invite. Cut down on lavish food. Don't waste money on huge dowries and gifts. But the least you can do is to have your loved ones WITH you when you celebrate a joyous occasion (and not send them to eat a lunch on their own).
My $0.02.
i agree!