While we can choose which field to order by when searching in advanced mode:
… we cannot choose whether we want to order ascending or descending.
Adding orderdesc modifier would easily make it possible:
order:likes is already descending, right?
So what you want is “the opposite of the normal order that this term means”.
Not sure about this, but… How about order:-views to start at 0 and go up, while order:-latest starts at the oldest?
struggling to think of use cases for orderdesc:likes or orderdesc:views, though I am open to possibly adding order:earliest (its quite rare to need though)
We should find a way to allow for opposite ordering for any ordering type (kind of a universal way of doing it), then easier to remember and use.
You never know what one could come up with 
I’d use orderdesk:likes to identify which type of material is the worst in terms of people likes and not create similar topics, or not include them in the lists.
orderdesc:views might possibly indicate topics that need some more useful information to get more attractions from organic search.
I think there might be more use-cases I can’t think of, why not just make it possible with a single operator.
I want this feature in order to support an “inbox” use case for processing forum traffic: I have a search that I want to sort by least recently posted (so that I can work down the queue of posts awaiting a response), and I can only get most recently posted (afaict).
You might want to consider using the Unanswered filter: /latest?max_posts=1.
However, I did also write a PR to add this sorting option:
Taking suggestions as to what the name in the dropdown menu should be, I don’t really like “Oldest Update”.
Je cherchais un moyen de trier les résultats par plus ancien (ordre chronologique croissant, ajout de ces termes pour de futures recherches sur meta…) lors de la recherche dans un sujet.
Je n’ai pas trouvé « Trier par plus ancien message » (il n’y a que Dernier message), mais j’ai bien essayé « Trier par dernier sujet » et cela a fonctionné.
Je pense comprendre la logique, mais les termes sont un peu contre-intuitifs dans ce cas particulier.
Un choix d’ordre chronologique croissant/décroissant serait, pour moi, un bon ajout, j’essaie parfois de le faire, et je l’ai fait sur d’autres forums qui le permettaient. Souvent plus pour le plaisir que pour chercher des informations spécifiques et intéressantes.
De plus, je me demande à quelle fréquence les gens trient par Dernier, par rapport au défaut « Pertinence ». J’utilise souvent « par Dernier » sur de nombreux forums.