There's a massive difference in perceived noise between riding a big capacity bike with slightly modded pipes at low revs and a 'ped with baffles removed at high revs.
When would you ever ride a big bike at low revs? Sorry but you are talking rubbish, many miles spent commuting in London with other motorbikes and big bikes are louder than a moped which has been modified.
In the future it maybe worth while thinking about of all the people you may have annoyed before you start acting pious.