the quick reply mod will never be a feature of phpbb as these are message boards not chat room
and the quick reply gives the forum a chat feel. I dare say it will quickly appear as a mod. The attachment mod is one of the single most popular mods so i can see why is has been added as a feature especially as it does not detract from the message board feel, like the quick reply would!
if that is the reason the developers gave you for not using the QR mod then that shows just how out of touch with phpbb user's they are and explains why this beta release is not directed at the end user but at developers in general.
It is not a community based release it is a Administrators/Developers release and will never be accepted by the community users as a forum of cohoice.
I can see membership to a lot of forums dwindling because of the so called features in phpbb3 if it is released and used in it's present form.
I have no doubts that my members will not take to it and I will of course remain true to phpbb2 with the mods that I have installed as the board of choice and I also have no doubts that this will be the case world wide.
As for the attachment mod I have downloaded and installed it on many boards only to uninstall it and of course the number of downloads shown against, does not go down when it is uninstalled so I bet less than 10% of the downloads of it are actually in use anywhere.
I visit hundreds of boards, all phpbb and all through links from mods/hacks and/or showcasing boards and very rarely do I see one with the attachment mod.
I bet the developers would have to look far a wide to find it as well so to say it is one of the most popular, is in my opinion, a long way off the mark.