I totally understand everyone has a budget and it’s sometimes awkward expecting your bridal party to participate in everything. With that being said, when asking someone to be a part of your wedding they are making a commitment to be there with a dress, the hair, makeup, bachelorette and shower. It comes with the gig.
The reason makeup is so important is, you're paying a photographer which is usually one of the more expensive vendors besides the venue, and they are going to be capturing your day with lighting and professional cameras, the average person doesn't know how to have photo ready makeup let alone for a 16 hour plus day. You can always tell in photos who didn't get makeup professionally done. Everyone's faces are what's captured, these are your moments and trust me they look better when everyone has their makeup done.