We can also look at this from the point of view that now Medium readers are able to select their mode of consumption:
A. the x page long article requiring time and dedication, and
B. (the snack-size), visually inspirational and chrystallized piece of thought sparking readers’ inspiration. Often with smartphone.
I’ve enjoyed Series greatly, and still take my time to read the Medium articles as well. With my mobile, it will probably be mostly about Series, and this might be also one reason behind the introduction of Series: providing an appealing mobile content consumption platform as an alternative to long-form text-based content Medium has been up till now. User behavior is contextual, and for me Series is a great addition to enrich my mobile content consumption with quality content.