What is the value of having an open return, wall register near the ceiling during the winter? Doesn't it just remove the heated air?

Should there not be two return registers with dampers, to circulate hot or cool air, respectively, by opening/closing them according to the season?

1. Top register, high on the wall which is open during summer to remove hotter air and send it back thru the A/C. Closed in winter.

2. Bottom register that is towards the bottom of the wall, near the floor, and that is open in the winter, to remove cold air and send it thru the furnace heater. Closed in summer.

My 40-year old house in Maryland had only two return registers in the upper-level, both near the ceiling and neither with dampers.

When a return, wall register was recently added in the lower-level, near the floor, the air quality improved greatly. The MBR (upper-level) has no return registers and is always too cold in winter, too hot in summer.

I want to improve the air flow to improve heating/cooling during winter/summer.

The wall registers are located across the room from the floor registers which supply heated/cooled air.

Thank you for all your skillful advise.