I know it’s cuz Frakes is still involved in trek (which like mad respect by the way dude got a gig in the mid 80s and it’s still earning him a paycheck) but Riker being the character who just like Shows Up in other shows is so fitting. Like that dude just goes places. Sure, the Titan has “official missions” but you know half the time they’re just going somewhere cuz the vibe is right. Everyone in Starfleet knows that man, not just knows of him, but has met him personally cuz he’s like everywhere all the time.