A faster spin speed means you can get things cleaner with a lower temperature of the water. Using a fast spin also extracts water, meaning that the clothes come out nearly dry. Generally, anything over 1,000 rpm is very good.
More weight capacity helps if you want to wash something heavy like curtains. A traditional household machine can hold around 6kg, so with a machine much bigger you may waste energy using it when only half full.
During a spin, machines can get quite noisy. With less noise the machine is not as distracting and you won't be restricted to using it at certain times.
With a delay start option you can schedule the machine to begin at a later time. You can also set the machine to wash at night if your electricity is cheaper outside of peak times.
Steam is a quick way to freshen up items that have only been worn for a few hours, or items that smell like food or smoke.
With a lower noise level for washing you can worry less about disruption and may be able to do a wash at night or while reading.