It can be very telling. On multiple fronts...
If you go from 2 tracks to 1.. this is presumably so you have more room for your 1 track. Which people assume would be to have a longer ride. Even if you doubled the train capacity, but you extended the duration of the ride.. that would decrease hourly throughput.
When you go from two independently cycling rides to one double sized ride you increase the exposure to reduced throughput. A missed dispatch of a smaller train = less people impacted than a dispatch of a larger train. So the hit to your throughput is smaller. Two independent systems also means a interruption means less throughput is lost due to that interruption if only half of your capacity is impacted.
The other thing about side by side seating is the vehicles are larger. Larger vehicles -> bigger ride paths .. you can lose that 'tight' feeling when the pathway is 50% wider due to a wider vehicle (even tho the envelop requirements are the same). Single lane road vs a double lane road...
But I gotta imagine there is no way in 2025 that Disney designs a new coaster with in-line seating. Just between accessibility, ride cycle time, safety restraints, presumptions over personal space, product availability... I would expect Disney to switch to a more modern conventional seating arrangement.