Agreed, Many of the CD's discussed by the Dev team or on these forums seem too short in duration, While longer CD's seem excessive it would serve to limit occurances far better since it may mean the player will be waiting beyond their days average gameplay, IE: they wont be doing it again until the next day/time they play.
I don't mind being able to log into multiple characters to check who is online but once you actually join the battle that lockout should kick in.
To be honest even that doesn't solve the problem, anyone that really wants to do simply has multiple accounts.
Since we dont know if the Devs will allow multiple accounts yet, there are some mechanics such as IP account tracking that can be used to mitigate multiple account generation (not perfect but it slows the average user, we all know a dedicated techhead or hacker will always find a way around such systems). And hopefully with multiple characters allowable to a single account the numbers of multiple account makers will be minimal.
If people want to buy extra copies then be my guest, Have multiple accounts to get around the system.