Nah...those other modules just sit there taking up memory...never used them, never had a need for them...but the rest of LR, library, develope and Print are great...glad they still enhance them.
Wow ... Adobe did something chez isn't fully behind and enamored with? Why I thought Adobe could never do anything chez would question ... is that sound I hear in the distance Hell freezing over?

Who gets to decide which modules are niche? Do you ignore all the comments from other Lr users (maybe not here but at FM, the U2U forum or the feedback forum) that consider the database features of Library as unnecessary 'bloat' ... that they believe a simple browser would be more valuable? ... Or ... that according to some stories and polls I've seen over the years, that it is a minority of Lr users that actually print their own images ... a lot of casual users (which are the greater majority, by your own previous comments here and elsewhere) seem to be intimidated by the whole color management process and simply use commercial options for their printing needs rather than investing time and effort learning the Print module.
So ... if Adobe looks at allocating resources to save chez more 'memory' ... you'd be happy if they let such modules die on the vine? ... Or would you lobby for the further inclusion or development?
Since you seem to need the book and slideshow modules and Adobe has no interest in them...maybe it is YOU who should look elsewhere.
Unlike you ... I have never suggested that Adobe ignore the concerns, wishes and desires other users have for Lightroom. I have never once lobbied or requested the Lr Team allocate resources only on what I desire ... I don't pay the licensing fees charged to others, why should I get to dictate their desires and considerations?
You see ... it was Adobe, not me, not you and not any other single user, that included a Slideshow module with Lr ... that came from Adobe on Day One. My only contention is, if they are going to include a Slideshow module, they put forth the same effort and the same level of attention to detail they have done with Print, Library and Develop (even though the heavy lifting for Develop is done outside of Lr) By doing so, the overall value of Lr would increase exponentially. Which would make the app even more attractive to potential users ... likely more so than a revamped Import dialog would.
Likewise, the Book, Maps and Facial recognition were added after the fact .... by Adobe, of their own free will ... again, if they are going to include them ... they should be consistent ... They did a fair job with Maps ... but dropped the ball in significant and unexplainable ways with Book and Facial recognition.
The fact that Slideshow and Books may not be as popular, as you would like to think, is not a result of, most users do not wish to create slideshows or books in Lr ... it has to do with the less than stellar approach Adobe has placed upon those tools. I contend, if Adobe offered such options on par with say, Print ... both would see much more extensive use building a much more loyal user base.
But you go ahead ... tell your fellow users they are not worthy of attention by Adobe and their licensing fees are insignificant because chez is more concerned about saving his 'memory' than if his fellow Lightroom users have the tools they desire ... some of which were included by Adobe since Lightroom's inception.