The first I've known for a long time, that I can't stop the machine and let clothes soak for awhile. I found that I could get really dirty/stained clothes cleaner with my old machine by stopping it and letting them soak. That's not an option on the HE machine.
The second reason has cropped up recently. Stores aren't selling HE detergents! At least my grocery store isn't. My favorite laundry detergent is Gain. I've even had compliments from guests about the sheets, towels, and their laundry. Now my grocery store is only carrying one brand with HE option and it isn't Gain. That means either buying a different brand or making a run to a different store.
But inasmuch as my machine is operating without any issues, it'll probably be awhile before I buy a new one.