I'm sorry to hear about your problems. The 7800 Wheels are very different than the old version.
I have a pair of 7700 Wheels and knock on wood they have not had to be trued in about 900 miles I have on them. I bought them used from a Saturn rider so they had miles on them before me.
One reason I bought them is with the old spoke design a good friend said they would be "bomb proof" even though I'm over 200 and the roads here are the pits. He has been right. I am a huge believer in hand built wheels but I got these at a great price. I like them.
Shimano was a big believer in their old spoke design. I've heard it mentioned that the change may have been due to Rolf saying he was going to sue since they are paired in a similar fashion. Who knows?
If you continue to have problems I sure would complain. They cost way too much to go out of true all the time. Maybe your wheels are a bad build. It happens.