I really like the box at the bottom, since most of the time I use it is to respond to the OP. Also, the "quick reply" link doesn't really seem to do anything. It puts the cursor in the quick reply box with a space entered already. Is that some way of tying it to the post I clicked on?
Either way, I'd really not like to get rid of the box at the bottom. I use the "quick quote" link more than anything on this board, and the full reply screen doesn't have the whole thread available, which makes it tough to quote people.
I don't intend (nor can I) take away the quick reply box at this point. As a user, I also use it frequently. When you click the quick reply links, it does link your comment to that part of the discussion instead of the thread starter. The space in the editing box appears to be a bug, possibly due to one of the older upgrades or changes adding a space in some file. Beyond that space bug, the current codebase doesn't provide really any feedback that the quick reply links under each post are working.
There might be some quick code changes that could make that box properly reflect what is being responded to. Though in general I've avoided many code changes to the board to help keep it easyish to upgrade.
As part of the upcoming migration to Andy's server, an upgrade to 7.5.9 might happen. Overall it's a big bugfix and code cleanup release. Work is being done by the new owners of the codebase to improve it one day, but no real timeframe. I've been seeing slow progress on that front for the past 3 years.