The big stage
The first reason to play as an opening act is the big stage. Press, professionals, live audience - at the own shown, there are a lot less of them. They’re coming without having to be invited. Nowhere else it’s possible to convince so many new listeners and by that raise your fame. The audience already knows the headliner. As a support band you have the surprise effect on your side.
The big moment
Playing before a big act also brings the thrill of the “big moment” - an argument you shouldn’t belittle while “only” being the stirrup holders. On the one hand it’s exciting and educational to share a stage with established professionals. On the other hand - let’s face it - name-dropping simply is a thing that always works. For promotional causes but also for the own experience. How come older musicians remember who they made music with more often than their own song ideas?
The big chance
Besides the marketing effects and the emotional reasons, the big chance to be discovered is a reason to play support shows. Often laughed at for being a dream - but also a product of strategic consideration. Often adduced as a success story is the band history of Silbermond. They started as the opening act for Jeanette Biedermann and now offer up-and-coming bands the chances for big shows and a lot of contacts in the industry themselves. Kraftklub opened for Beatsteaks, Wir sind Helden for Banana Fishbones, Queens Of The Stone Age supported Monster Magnet and Muse supported Bush.
If it’s useful for you to play a support show and maybe even invest money into it is a thing you have to estimate yourself - but there are quite a few good reasons for doing so.