Because G is also really just consumed by the people, wouldn´t it make sense to measure all the things that people consume to measure the prosperity of an economy?
At the end of the day, people in an economy with C = 100 and G = 80 would get more stuff done, than people in an economy with C = 120 and G = 20.
In my opinion it is even better than the GDP in the short term, because you don't really care about the amount of investment in an economy, you can´t be sure about the effectiveness of those investments, the only thing you really want is that you would be able to buy more stuff (C) and get more govt. services (G).
So if we would think about a closed economy, than people would get more goods and services in an economy with C = 100 G = 80 I = 10, GDP= 190 than in an economy with C = 120 G = 30 I = 50 GDP = 200
I was thinking about writing my bachelor´s about it, but I need to hear your opinion.
PS. We could also modify it and use the MEDIAN WAGE + G/NUMBER OF PEOPLE, so that we could get the real prosperity level of an average citizen, which we can´t get using the GDP or just the wage data, because it´s better to get a wage of 100.000 and 50.000 in govt. services than 120.000 and 10.000 in govt. services