I've always thought it was for reasons of "continuity"
They want to present a site that is consistent in it's look and feel across the board. That's one of the principals of good web design. They felt if they could just export it to the new format, they'd have the best of both worlds. I know that the techs could have done a better job than they did, not from any lack of talent or caring but simply for lack of time to address it all. I get the impression that at some point someone high up decided "OK, enough money has been spent on this, let's move on to something else" and the techs were just pulled off the job to deal with something more pressing to the overall operations of the company.
I understand why they did away with the old Gail's. Look how many features are possible today that the old Gail's didn't have: private messages, edit your post, a way to distinguish which posts have been read, a faster search. They wanted to add those features and bring not only the technology but the functionality into the 21st century. And the kind of forum that they did end up implementing is very popular on the Internet. If I worked at Epi I probably would have done the exact same thing. I imagine that they were completely dismayed at the reaction to something that they were probably quite pround of, and whoever that was, because it was probably a web designer or tech like me and not one of the powers that be, I quite feel for them actually. Another community might have loved that new board.
Watching the whole thing happen was a fascinating lesson for a web designer to watch. NOW if I were to make a big change like that, I might set up examples of several different types of boards and privately invite a group of the most reliable regulars to evaluate them, plus closely question them on what they do or don't like about the old board the new ones being evaluated. However, I have had the benefit of watching this all happen and I'm not sure I would have had that foresight before this.
Whoa...I am feeling quite verbose today I guess! It must be that I had a medium coffee at Tim Horton's instead of my usual small...