Except that they all cover the new political rival on the scene. It would have been more interesting to allow the Pact to be slowly revealed. Now we've got "Hey, it's the Typhon Pact!." No real background on it. No mystery. They're simply presented as a going concern.
You're reading too much advance publicity. The Pact membership
is revealed across the four books, with more intrigue, and details of new members/developments revealed as the books go on, but the books also work as standalone adventures, set against a backdrop of post-Destiny fallout.
1 - all the 24th century books are in the same time period.
Well, considering that Marco and Margaret fended off a barage of "When will the 24th century books line up?" over several years on this BBS, this is an example of Pocket never being able to please everyone.
By popular demand.
It makes you feel that you could miss out on a big point if you're not reading them all.
Or it doesn't. Other standalone ST books often mention previous offscreen and offpage adventures that were never in any other book, episode or movie. It's like Sulu and Kang being revealed as having had an extensive adversarial background before ST VI, but not revealed or even hinted at until VOY's "Flashback".
People could (and do) view "Flashback", or read its novelization, and worry that they've missed an unseen series of adventures where Kang and Sulu do battle during the TOS movie era. Of course, we eventually did get a novel ("Forged in Fire") that tied these connections to DS9's "Blood Oath", but that was
many years later.
Just look a the topics on "what do I have to read next/first".
By a tiny proportion of the readership. And way back in 1980, I was often asked by ST fans - hundreds of times! - whether they had to read Pocket ST novels in number order, because the Bantams had not been numbered. Other members of my club used to say they'd only read the novels that "really happened", and they'd ask why events of the 80s novels were never mentioned by the ongoing TOS movie series. This was long before Richard Arnold started to talk about what was canonical and non canonical.