Andy Adams of The Theme Foundry:
I’d like to suggest that competitors like Squarespace are going to start eating WordPress’s lunch on the “ease of use” front if WordPress does not adapt.
Adams goes on to say how important the theme customizer is to helping WordPress to keep its competition at bay.
Remember, Matt Mullenweg said that they are focused on "radically simplifying what we currently do". This is key for WordPress to continue to be the platform of choice for so many sites. There are much easier solutions out there – though arguably more or less powerful – but WordPress really could use a major (radical as Matt put it) rethink because the years of adding features have made it much more complex than its newest competition.