Because the AC40's are designed to be easier for Youth and Womens teams to be able to sail. Its a turn key package.The last AC was a bore fest. Just because they wear helmets and go fast on foils doesn't make it exciting for me.
It's now all about foiling with a little bit of sailing thrown in.
If the AC40 is the F2 to the AC's F1 why have auto height control?
The teams themselves have their own LEQ12, which they'll no doubt use to develop their own control systems, but the current AC40 is one design, and is designed for ease of use.