So, with some of the context set, I'll try to address the concerns:
1. The length of submission is too long.
I suppose one way we could address this is to remove the lower bound on the word count. It seems in some sense notional but it seems strange to change things right ahead of the deadline. Would this put one's 600 word abstract at a disadvantage to someone who has submitted 1,100 words. I suspect it would.
If I am reading correctly, I think that Jeremy is suggesting that the increase in the number of words will systematically exclude graduate students. I can't imagine that graduate students are any less capable of producing 400 more words. I personally am probably less capable of that now than when I was a grad student. We could, I suppose, ask Sheizaf Rafaeli whether the 1,000 word cap for IR5.0 resulted in a reduced number of graduate submissions. If it did, I don't think I noticed it.
I did not mean imply that, but what I did imply is that the number of student acceptances has seemed to diminish over the year. However, here i return to the professionalization question. People who are more competent at producing abstracts for conferences tend to get into more conferences. That is a skill set that is learned, so newer people to the profession tend to have less access than older people. The more words that we require them to write opens up more possibilities for someone to write something that will get them rejected. Are we accepting or rejecting more of any one category of people, surely those statistics exist and are things that are discussed by the executive. The question in the end is what are we, organizationally, supporting by requiring more and more, combined with stricter modes of production? I understand the arguments you put forth, but I want to suggest that there are other implications to the system being put forth than you suggest too. I argue that the new system ads additional disciplinarity and requires additional professionalization. Those things are, i think going to be antagonistic to interdisciplinarity, grad student participation, and international participation in the short and long run. But i could be wrong, but I would be remiss to not point out that possibility and warn against it.