For those still complaining about Arcade being expensive, this is great way to rake up Credits to unlock Kommandon Ld and Nega D Ld, so I see no problem in the staff rotating the Legendaries weekly without releasing Kommandon Ld and Nega D Ld. In a few months time, you probably would realise 300 Credits is not that significant. Plus the upside is you get a decent Collector for the 372 Stars in Season 1.
In fact, if you are patient and willing to give up on a few New Blood Packs (make sure that a not so overpowered character is released though), then it makes sense that Kommandon Ld and Nega D Ld is not released. Just also be grateful that Season 2 and Bonus Season are free.
I wonder when Season 3 Arcade will be out? Maybe next year feature H1v3 or R4pt0r5? (Play on the clan names Hive and Raptors)?