Comment by EndsOfnversion

From memory, the primary advantage of the 386SX was the ability to use a cheaper 16-bit motherboard layout and components. The lack of a 32bit bus mattered less when most software was written with 286 compatibility in mind, and the ISA bus was only 16-bits wide, which limited the utility of the 32-bit bus for fast graphics transfers.

The reduced 24-bit address bus was never a significant bottleneck during its commercial lifetime, as little consumer software at the time would require more than 4mb of RAM, and by the time it did the 486SX (32bit busses with no maths coprocessor) was the new value champion.