That's what I miss when Titan is involved in a crossover rather than a stand alone. The primary interaction is between the major characters for the most part. I'd rather learn more about the varied characters on the Titan. Given the choice between seeing how Ezri gets along with Riker or finding out more about Gibruch, Sen'kara or Ooteshk and how they interact with the crew and a new alien race I''ll choose the latter. The books offer the opportunity to delve into aliens in a way that you can't in a 44 minute TV episode.
What's the flavour of each of the series? What's it's voice? What makes it distinct from the others?
See, this is why it's a mistake to assume that
Destiny is a model for anything that follows rather than a unique event. Most Trek novel crossovers don't involve the casts interacting directly. Rather, they involve each cast
independently dealing with a separate aspect of the overall theme or situation. So the distinct character emphasis, flavor, and voice of each series remains.
Destiny was unique in that it featured heavy interaction among the crews, and even it didn't really have that until Book 3.
Gateways had one scene featuring direct interaction among the TNG, DS9, and NF crews while otherwise keeping them separate, and of course the VGR, TOS, and
Challenger crews were all completely separate from the rest.
Double Helix had mixes and matches of TNG characters with various others, but no whole-crew interaction. Otherwise, every crossover has kept the crews entirely separate:
Invasion!: Each crew deals with a separate aspect of the Furies crisis at a separate time. One guest character crosses over from the TNG installment to the VGR installment, but no other character interaction occurs.
Day of Honor: Four totally separate stories whose only connection is the day they take place on (in different years) and the fact that they all involve Klingons. Kor guest stars in the TOS and DS9 installments, a century apart, but cross-references are minimal.
The Captain's Table: Six independent stories linked only by the mode of presentation, narrated in the first person by the captains. The frame stories in the Captain's Table bar involve some recurring characters, but there's no direct interaction between the featured captains; one leaves and then the next enters. The actual stories told by the captains are completely standalone.
Section 31: Four totally separate stories about the different crews' separate interactions with S31 in the course of various different adventures. The S31 connection in the VGR installment is tenuous.
The Badlands, The Brave and the Bold: Both duologies consist of four stories showing the respective crews dealing with separate aspects of a common problem at separate times, with no direct interaction among the featured crews. TB&tB has each featured crew interacting with a guest crew (and is actually told from the guest crew's perspective), but there are no lead-lead crossovers, only lead-guest crossovers. (Although Klag subsequently became the lead of his own series, so that could count as an exception.)
So what you're complaining about as your problem with crossovers is something that
is not actually done in most Trek crossovers. It happened only in
Destiny, and very slightly in
Gateways. It's the exception rather than the rule.
Most Trek novel crossovers are intentionally designed so that each installment can be read independently. If you're only a fan of a certain series, you only need to read the book in that series and you won't miss anything. If you can't find every book in the crossover, that's fine, because you don't need to read them all.