Few reasons for this;
1.football grounds are built so the crowd are as close to the field as possible...a running track is seen as an abomination. Murrayfield has a pretty big gap between the crowd and the field.
2.those who attended the 7s weren't your normal Rugby crowd...many of those in attendance would have brought their own excitement at being at an event in the Commonwealth games, also being in Glasgow there would have been more of a working class crowd.
3.Sevens isn't bogged down by line outs and scrums...open running is what most folk want to see. Always loved watching Fiji when Serevi was running the show.
In terms of the standard XV man Rugby, 7s is probably a tad too loose (one break and your away)...13 man Rugby in this form would be just about right I'd say. No heffers, no bogged down play...13 athletes playing attacking Rugby (in other words Rugby league but with Rugby Union's tackle rule)
