>- @> contains range/element >- <@ element/range is contained by
I'm not a heavy user or range types, so I can't really judge how useful that is in practice, but it seems like a fairly natural extension of the existing operators. I mean, if I understand it correctly, the proposed behavior is equal to treating the element as a "collapsed range".
In that talk, I mention the need for exactly these operators, specifically for an extension called range_partitioning which had some logic for "If I were to insert a row with this value, what partition would it end up in?" which allowed for a subsequent COPY operation directly to that partition. That logic essentially binary-searched a series of ranges, so it needed an "elem <@ range" as well as << and >>.
Yes, constructing a collapsed range was the work-around I used in the absence of real functions.
That extension has been replaced by real table partitioning and the planner itself now does similar logic for partition pruning.
So yes, I've had a need for those operators in the past. What I don't know is whether adding these functions will be worth the catalog clutter.