My idea's for Readynas OS 6.2

Some of these things are already in OS6.

=> Folder management for backups and sharing is the most critical thing missing right now. I really hate to duplicate my data because I want to share a specific folder with someone. I also want backups to exclude some files/folders.
=> For firewall, a fully fledged firewall with an interface would be nice, but you can use iptables for basic needs though I couldn't configure fail2ban (you miss the log, you need rsyslog, and then you get startup errors that you solve by adding a sleep timer in a script, and then you have an iptables problem that I haven't solved yet).
=> task automation (scrub, defrag, ability to do partial scans with the anti virus (on a scheduled time with an exclude time range in case scan is not finish when you start to work)
=> advanced monitoring (Cacti isn't quite that, I would have shinken instead and more options in the interface to show graphs).
=> progress bar for backups, virus scan and defrag
=> disk spin down

I don't agree with you for built in things, it will add weight to the OS and since RN102/104 is not powerful it's not advisable for those models, I prefer to have reliable packets aside that you can choose to install or not (and that may integrate on the interface once installed). You already have PHP/Mysql/PHPMyAdmin, Qtorrent and Transmission.
SMART, HDD health are already integrated. For hibernate you have a scheduled shutdown/boot functionality.
If you want HTAccess for password only, you already have it too.

I don't see what you mean by "more security settings for users", I'd just like to be able to set ready cloud rights within the local interface but apart from that I don't see what you can add.
SMB settings are already good, you have an add-on to switch the version for compatibility. What settings do you need ?

Fail2ban would definitely be an eagerly desirable feature. For the moment I have a RN104 running as an RSYNC-over-SSH backup server, for a few RN102 clients. Problem is that you can't explicitly tell which SSH port you want to leverage when configuring an RSYNC-over-SSH backup job on the RN clients. Thus I'm forced to expose my backup server's port 22 (i.e. SSH). And guess what ? I have numerous daily SSH intrusion tentatives on my RN104 (as much as 5000 a day, sometimes). Fortunately I'm using 20 characters long password (generated with Keepass), making a brute force attack rather difficult. But still, I don't quite understand why there is no built-in defense mechanism (Fail2ban or alike) in ReadyNAS. This takes me to consider ReadyNAS as a great product, but not a professional one.

And at the first place, I don't get why we still can't specify a port when defining an RSYNC-over-SSH backup job, which sounds like a very trivial features in Linux world, to me. But this is another topic (see http://www.readynas.com/forum/viewtopic.php?f=31&t=73441)

Cheers
Jean-Marc