It seems like Falcom doesn't have what it takes to climb and the higherups know it. According to the history documented in the Falcom music spreadsheet, Falcom is a "black company" nobody wants to work at. Most of the staff quite Falcom during Ys III's development. Chairman Kato then instituted a no talking and no crediting policy for fear of employees gaining a reputation and thus leverage. People don't want to invest a lot of time and effort into work that isn't going to be credited or work that they can't talk about, so they don't apply to Falcom and Falcom struggles to acquire good talent. So what you're left with is a dwindling pool of talent. (Talent retention is a general industry issue, Square Enix suffers from it, but here it's especially bad). Falcom used to have a large, talented music team, but now almost everyone is gone and they're just down to two people now.
Without good talent, Falcom struggles to make good games that can be lauded and become hits on their own merits. But the higherups don't want Falcom to die like all of the other mid sized Japanese game devs that perished during the 2000s and 2010s, so they're playing it safe by milking franchises with long tails like Trails and Ys. If one person buys a Trails game and likes it, then they might buy the back catalog of Trails games (which is... what? 12 or 13 games now?), which gives Falcom a lot of money ($540 in games). So its in Falcom's financial interests to keep dragging out the Trails series as long as possible to inflate the back catalog of sales they can make money off of. Which is why we have a 1,000+ hour long series where the plot hasn't progressed in years, hardly anyone has died, and nothing has really happened.