One of Banksy’s messages being about capitalism as is his art - Festival (destroy capitalism), I found it ironic that his merchandises are sold at the exit of the exhibition.

His art being curated like that is missing the point.
I think his arts express important yet neglected pieces of the world and I think it is more valuable while being on the streets where he created. 
It gives us a regular reminder to be more mindful and aware of lives we live every single day as we walk pass his art. Not when we visit art galleries.
However, I have to agree exhibition is a great way to spread the messages around the world and over all, excellent presentation and experience. Thank you.