I know it's all about marketing. But why did SME choose EXO to put all that effort into? Because the company themselves saw the potential with them more than they probably saw it with their other groups (imo, I bet if SJ/SNSD had debuted later on when SME was more successful, they'd receive the same treatment). They took the risk because they thought it was there. You don't gamble on something without trusting you have a good chance of seeing some of what you expected returned.
So the way I see it... EXO naturally had enough potential for star power to SME for them to be willing to go all out. NOT saying that they would do this well without all that promotion. Just that some credit has to be given to the boys themselves as well.
I do agree with having more C-members adding to the popularity. That was a smart move by SME.
The way they react to things is just how they are. I know people want them to be more "excited" but... really, why fake it when they're all smiles and appreciative? That should be good enough? I feel like people always want some crying fest or excitement over level 9000 for it to be legitimatized as enough. Maybe it's because I react the same, but I don't get why people expect all that...