When pg used a todo list as an example app to challenge email, this was to be expected. A million todo apps everywhere. People have so little imagination.
I don't think pg is to blame for this... todo list apps are inherently simple to design and build. If anything, they're a great 'first app' for new or aspiring developers, so a marketplace flooded with (many shitty) todo apps is not surprising.
I applaud the effort and entrepreneurial spirit and even the quality of the UI work. I'd question the judgement when there are so many to-do apps out there already.
I am agree with this... It's great staying strong in the things that you believe. I am not sure about questioning him though. Starting in a dense market is not an excuse for failure. There were too many "searching engines" back in the day and that wasn't a problem for Google.
Also, companies often evolve in different directions from where they start. Take Instagram for instance, they evolved from a social network and in the middle decided to take another path.