You can't be creative as a Engineer as reasons stated, and also because you spawn with 25 metal 10 plastisteel and the only good things you can spend points on as a Engineer is Plastisteel (can get a maximum of 60 from 45 points) or Claymores.
Metal gets killed in a couple swipes while Plastisteel can survive a Queen screech + T3's and can be welded to repair it. Its literally the only reliable cade right now.
Claymores can insta kill or crit xenos if placed on offensive chokes / defensive chokes that most xenos go to.
Everything else is useless due to how powerful and tanky xenos are now. On top of that you don't even get enough of said useless cades because you have to rely on map resources (recycling) or Requisitions (be lucky and order metal first). Both are unreliable.