Is this a new trend?

Could be a number of reasons.  Internet ads are controlled based on algorithms.  I also think that younger buyers don't have large houses (or houses for that matter) so smaller speakers work better in apts, condos, or small houses.  And, smaller speakers with a woofer are really sounding good.  I listened to a pair of B&W bookshelves with a Rel sub and was impressed at the sound in relation to the system cost and space required.  

If you triggered and interest... then it can pop up all over. Once you notice it, then you start noticing them...

@ghdprentice

This could be true! Lately I’ve been marveling about the high sonic quality of bookshelf/monitors, often seeing the Vivid Kaya 12 advertised. Another ad TAS April 2025 for Crystal Cable Minissimo. Stereophile April 2025 reviewed the Vovativ Hagen monitor.

I think the speaker on a stand is a more appealing, sleeker look. Most important is it allows for better subwoofer performance rather than having the woofers connected in the same box.  

The term "bookshelf" speaker isn't really a fitting term for many of the stand speakers being used.

yogiboy, Acoustic suspension was instrumental in the early design of small speakers but it is essentially dead these days. Thiel/Small research into the design of bass reflex speakers allowed the design of small ported speakers which are more efficient and bassier although usually with less bass definition. Today the concept is misunderstood and almost everyone including reviewers call any closed box acoustic suspension when it almost never is. Acoustic suspension is a special variant of closed box and all closed boxes are not acoustic suspension. In fact the drivers today have design characteristics for bass reflex and can't work properly in acoustic suspension boxes. Edgar Vilchur must be rolling in his grave after his concept once had 2/3 of the audio market before Thiel/Small.