Currently this is auto-set and something we should open to a larger discussion if we change the default behavior since there are a lot of customers that depend on this.

I hope this setting is built-in too, it's kinda annoying everytime I had to poweroff again when it's not suppose to be rebooted. Thanks!

I don't mind that being the default behavior, but I'd like maybe a checkbox to prevent it from starting afterwards.

+1 for checkbox. in a clustered setup if I need to resize a machine that can't be fast-resized it is imperative that the machine NOT boot after startup otherwise it starts altering the cluster state.