MARC stands in the way of innovation
From MARC must die!
The cleverest people will always be outside your own organization [quote?], or even outside your own field of interest. MARC is a massive hurdle for clever people outside libraries that would like to do something interesting with our data.
Related to this is the fact that using library specific formats makes it hard to take advantage of innovations made in other fields and areas. Being stuck in our own little corner means we are not able to take advantage of innovations made elsewhere.
Regional MARC dialects mean that in order to take advantage of a new product that relies on MARC data (e.g. a free software system), the first thing that has to be done is adapt it to the regional MARC dialect. That means re-implementing functionality that is already there. This takes time - time that could have been spent on implementing new and better functionality for users.