Toggs is on the money with this one. The pause is there to give the motor a break before reversing to spin, along with the other reasons listed above. Reversing motor washers have a pause between wash and spin to allow the motor to cool for a moment before reversing.
Early non reversing washers used mechanical means to shift from wash to spin - such as the AMP Maytag, Frigidaire Unimatic, and the solenoid operated Speed Queens, amongst others. This was at a time when dual rotation motors were expensive. Once the cost warranted their use, simplified mechanisms came into play - heilcal Maytags, revsering Speed Queens, Rollermatics, Norge/Wards, etc. Well, maybe not the Multi-matic... ;-)
Ben