Do you release how much resources and effort it takes to destroy a OKW HQ in 1vs1? a lot and a lot of time. Otherwise OKW faction wouldn't be viable. If you decide to play aggressively and be push back, why should you be given a 2nd try with a KT?
Depends on how they were placed and how well the game is going for the OKW player. A poorly placed truck is pretty easy to destroy (a lot of it depends on map and shot blockers). The more important question is
why shouldn't they be given a second chance? Destroying a truck is a big blow and gives you an advantage in a game, why isn't that enough? What you are suggesting is "I want destroying forward HQs to be a game ender".
The OKW player has already invested significant MP/Fuel on all 4 SWS and buildings. That is a BIG investment. Resources are resources regardless of whether or not previous trucks were destroyed - if an OKW player can amass 600+ MP and 300+ Fuel while on the backfoot from previous HQ losses then why shouldn't they get something for those resources in the form of a KT? (Think of what that MP/Fuel buys for the Allies!) Just because an allied player can't capitalize on an early advantage doesn't mean OKW should get saddled with an additional handicap when they are already (presumably) losing.
I mean I get it... its frustrating to feel like you should have won only to have a KT turn the tide but its not like the current KT is the old one that can YOLO into a 4 AT gun wall. Its not gamebreakingly OP.