Forum viewing is a great feature and I think Xenforo team should consider to have this feature, it will save money for more people.
Although I know I can get the answer like it will cause issues on loading or performance. But if we have this feature then we can turn on/off it depending on per purpose.
On our forum
https://www.webmastersun.com is using forum viewing and I think i will need it to have on Xenforo 2 when update to this version though.
Just curious, it is an addon or just your design?