Using it in the field is 10/10 viable option.
No it is not. Nobody does this unless you feel like losing 10 fuel for no reason
And if you are letting your opponent to faceroll you to your base well that is a deserved loss.
But only for US? Cause nobody else has their healing get 1-shotted
German bunkers should need pop-cap? Even concrete bunker don't worth it, because they are way too easy to destroy, same for german bunkers, simply build a PaK and hit it 4 times.
*All bunkers, FPs are included here
You can make them cheaper in cost when they have popcap, which is a better tool to limit them than resources