There are many reasons why someone might choose to engineer:
1. to win wars seems obvious but there might be much more to that.
2. To prevent losses, yes the war streak starts over but the idea that they didn't lose holds true.
3. There is an idea that spartan warriors wanted a death on the battelfield. The are simply not going to just roll over and die however. It must be earned.
While I wouldn't consider myself an engineer as many on here say, defenseless only, I would say I'd rather do all that I can within the rules to win by utilizing the best strategies available than lose by purposely following weaker strategy that might make the war closer. I want a good tight war vs someone worthy of it. I would rather have a "cheap victory" than lose by dumbing me down to the competition.
As my signature says, "If you're not smarter than the guy you're dealing with you lose." Why should I have to follow a lesser strategy to get improved competition?
"You failed to utilize the most effective strategy by not using the most available resources to affect your outcome." You are free to follow any strategy you want and if you choose to follow a strategy that you knowingly hurts you in war match making that is your choice but don't tell me that I have to follow you.
Finally, "I play to win. You play to see how tough you are." Some play to say I'm the better attacker, aka I'm tough. I play to win and it is fun. My current war is a tight war and we will probably lose because I messed up on 2 attacks, not fun, but overall fun war that was earned by having a battle of strategies. I might have to have a few "cheap victories" to get that one, but when I do watch out cause its a war.
btw you mention, "why do they want cheap victories and not tight wars that most people enjoy?" but if you look at the forums many claim that engineering is all over the place therefore this statement would be incorrect. Many seem to enjoy the cheap victory and only a few want tight wars.
Edit. Ended up winning 43-42. Their #1 got a 48% zero star.