It is a long time since motorcycle racing was genuinely mainstream. This is a minority interest sport and road-racing is a fractional niche within it. If you went to any town centre (except perhaps in Ireland) and asked 'who is John McGuinness or Michael Dunlop' then you be lucky if you were greeted with anything other than blank looks.
The TT exists because it is the original, it is completely unique and it has the history. It really is the 'Road Racing Capital of the World', if you talk about real road racing anywhere in the world, then it won't be long before the conversation turns to the Isle of Man and the TT.
Some of us live and breathe the TT, and it clearly is a major part of the pasts and futures of many of us. For the remaining 99.9999999% of the world's population, it doesn't exist - except in the very occasional, and fleeting, sensational headline.
This is the heart of the reason that the World Series won't fly. The TT Brand may be strong but it won't have the power to generate the level of popular interest to elevate it from its niche and into the realm of viable commercial proposition.