The modes in the channel central dialog are there because they are the default modes of 99% of every IRC network (if not 100%). I find that the majority of people use /mode over the channel central dialog anyway, it's a much quicker way to set modes. The channel central dialog is good for changing the topic AND setting different modes at the same time.
Another problem would be the difference between the same mode chars on some networks - for example, +R, as Coolkill explained, prevents unregistered nicknames joining on DALnet - +r means the channel is 'registered'. On Undernet however, +r has the same effect as +R on DALnet. How is mIRC meant to tell if +r is the 'registered' +r, or the 'prevent unregistered usernames entering' +r? I'm sure there are various other modes that are like this. It's worth noting, users cannot set/unset +r on DALnet. Perhaps there is a workaround, a way for mIRC to grab some sort of info?
Personally, I like the way the channel central dialog is now, and for what I use it for, I see no need for change.
Regards,
