There is absolutely no doubt that key senders (whether software or hardware based) are providing a form of automation but as Blizzard states this is perfectly acceptable for them. Macros are another form of automation that Blizzard permits in game however. Both of these tools are obviously essential for multiboxing. Surprisingly the anti boxing people hone in on the key replication being unlawful automation but don't have a problem at all with macros...

The anti-boxing argument should therefore read: "It is unfair that other players have access to automation that I myself do not have the time, money or intelligence to utilise!!1!111".