Thursday night, I was booked on Flight 805 from BDL to MCO with a stop (but no plane change) at BWI. About halfway into the flight, the captain informed us there would be an aircraft swap at BWI, and the three of us continuing passengers would have to deplane, and get on the new one. The entire flight crew - captain, co-captain, and FAs, had to swap as well. He further informed us that the existing plane would be returning to BDL.

Given that the two planes are identical as far as number of seats.... what is the reason for this? If they needed a plane to go back to BDL, why not just use the plane that we had to switch too, rather than making an entire flight crew and 3 passengers go from one terminal to another? The new plane had no continuing passengers from its original itinerary when we got on board (the 3 of us were allowed to board first, after the pre-boards).

As we were taxiing, the captain got on the intercom again and apologized for the aircraft swap, and even said "Yeah these things don't make a lot of sense to us either."

Can anyone shed light on this? There's obviously something I'm missing....