I agree.
If those features are there, pressure will build to improve them. Diverting resources into competition with much bigger, already successful programs. While carrying a timeline albatross around the neck.
The vast majority of fiction writers never have a need for a timeline program. Even history writers rarely need something so detailed. And, in general, writers like relatively simple and intuitive interfaces whereas AT encourages a complex set up.
I don’t see that adding such features will bring new users. I can see that it would simplify life for some current users, if it is done well enough to make them give up their current programs. I already know that wouldn’t include me; partly because it would need to add a ton of new features, but mostly because the UI wouldn’t fit my needs when writing. But then, most of my timeline needs are simple and don’t require the number of options already in AT; for me, AT is something I use rarely and only when absolutely needed.