IMO, it's actually preposterous to describe our more progressive politics as trivial or agenda-driven; after all, what is the point of us being communal creatures, living together in towns and cities - and families - if we aren't going to encourage communal harmony? If we aren't prepared to 'tolerate' and consider views and lifestyles which may be different to our own? What is the point of our existence if we're either stubbornly solitary or else forever hovering, uncommitted, between community-spiritedness and blithe self-interest? These aren't, despite appearances, strictly political points...
More specifically, there are a thousand - and doubtless many more - lightweight entertainments, throwaway shows that young people can be thrilled and distracted by; Doctor Who could be considered one of these. However, devoted fans would be the first to assure us that Who is actually worthy of serious consideration and near-study, its themes deserving of both celebration and the status of importance. Very often, those constants, those themes are universal - not merely the age-old dramatic devices such as narratives of good versus evil or the virtues of heroes and heroines, but also the true and central themes: those of companionship, team work, intelligence actual and emotional, the common good. What better things could be taught, by such examples, to the young people who will inevitably succeed us? Who is a shining light, essentially a lesson told in love, with a view to promote better things and better lives for future adults.
Like all serious cultural presentations, Who cannot remain unchanging, even if it represents a certain reassuring and nostalgic comfort to many viewers; it has to engage in contemporary matters or, in time, die out; to find itself irrelevant to its potential next audience - those whose convictions and concerns might well differ from our own. Those who might desire something deeper than time-passing, empty entertainment from a show that is renowned for a certain subtlety of thought far distant from its popular image of seemingly tinfoil-dwelling villains and silly scarves and celery. Being young, such new viewers are yet to learn subtlety of thought; and so they require simple lessons. If Doctor Who is - as has been alleged - occasionally heavy-handed in its messaging...is that any wonder, is this method genuinely unnecessary? It's actually vital; because, like the Doctor, the show's creators see the bigger picture and they see that some 'agendas' are worth promoting...for the good and future-good of us all.