Calls to, for intance, iplot need the first argument, data to be a “list of traces”. However, often you just want to pass one trace and in this case the plot is not shown, wouldn’t be convenient to accept as well data being a single trace argument as well as a list? or at least convert single traces to a list with length 1, like this data=[trace], but do it behind the scenes, transparently to the user.
I expect this behaviour to be more intuitive and closer to how the plot function of R works.