The right of the dot thing is overrated among domainers. Don't forget it's marketing...
Around 2001 a couple TLDs like .biz .pro .aero were released and back then there was media coverage too (and expectations).
It's not like the public has never seen that before.
In recent years we also have had roughly one new TLD launched every year. There was media coverage too.
But there is a difference between 2001 and 2012.
Back then there were still opportunities for contender extensions to emerge. Today it's much more difficult because .com and ccTLDs are now deeply entrenched.
Of course we could argue about the reasons why almost all new extensions have failed. Many are truly bad, irrelevant, badly promoted, unneeded etc.
But do you think the new strings that have been applied for are any better ?
Most are doomed.
As always the lessons of the past are quietly discarded. Some people always think they will succeed in spite of the overwhelming pattern of failure.
Now if you look at it, even a dumb TLD like .tel can still be viable financially with defensive registrations. That doesn't mean there's money waiting for you. Domaining thrives on the greater fool theory
I agree the timing for .co was good, imagine if it had to compete against hundreds of other TLDs launched at the same time. Also imagine .co without the marketing. Nothing special.