Odd, most League fans I speak with are familiar with Sevens and quite a few like watching it (especially over 15s), but there is always a few hardcore ones that hate rugby no matter what. Several IRB 7s coaches came from League backgrounds, and have all stated that 7s defense/attack more closely mimic League than 15s, so any open minded League fan should pick up on Sevens quite easily.
Now the standard in most matches in Glasgow was actually poor with so many minnows (ie Barbados, Uganda, etc) playing. The Olympics will not have any minnows (non-core IRB sides), so the standard will be much higher across the entire tournament.
It is also interesting that 171,000 people went to the 4 sessions. That equates to 14% of the 1.2million total tickets sold at all Commonwealth Games events!
I don't think this exists