My take is, if you wanted to differentiate the morale of your forces compared to a terrestrial enemy, you would try to make everyone (including your enemies) believe that you possessed extra terrestrial technology.
What would be more of boost of morale than believing your side had mythically advanced weapons, and that your work was helping advance technological superiority?
1. You will have to keep very secret that this is what you're doing
2. If you do, your own officials will randomly start to believe you. And why would they believe you when you tell them it's all a hoax - after all, you're admitting that you're a manipulative POS, why would they believe you now?
Organization-level lies fry people's brains - including that of the liars. Probably especially of the liars.
Your point stands, but it's worth separating "Wunderwaffen", which over-promised but delivered something, from post-war pure fantasies like Haunebu and such.
The Me 262 was perhaps the only one that had positive ROI. Others, like the type XXI "electrical" submarines, and surface-to-air missiles, just came too late and proved wildly successful after the war. Yet others were just useless, like the V1 and V2. Kinda crazy that both sides kept trying terror bombing of civilians - it was never anything but a giant waste of resources that increased the enemy's motivation. And it's occasionally still happening in current wars!
I'd distinguish between the V-1/V-2 style terror bombing of civilians (high cost, small n, minimal-in-context physical damage caused), and the massive bombing campaigns. The latter did result in very large scale diversions of resources on the receiving end.
In WWII, some of the "terror" bombing stuff had high morale/political/propaganda values on the sending end. Such as the aptly named https://en.wikipedia.org/wiki/Doolittle_Raid (And by many accounts that last one had a very strong, if short-term, effect on Japanese strategy.)
In modern-day contexts, it might be helpful if there was an unflattering term for "looks like a terror attack, but the actual goal was to make the bomber feel better about himself". One can at least daydream that that might discourage a few violent nut jobs from hooking up with sounds-good-enough-if-you're-crazy excuses. Er, I mean "noble causes".
Only thing that terror bombing caused was to make sure downed foreign bomber crews were lynched by the local population if they were unfortunate enough to survive their shootdown and rallied the civilian population behind their respective regimes. An argument could be made that terror bombing may have prolonged the war.
I see that exactly the same way, terror bombing is for the "sending" side.
And industry bombing has indeed been very effective! Bombing of airfields, too. The Luftwaffe was reportedly (according to UK military leaders) weeks away from breaking the RAF with that before they gave up. Probably not really because people underestimate their own resourcefulness when the going gets tough!
What would be more of boost of morale than believing your side had mythically advanced weapons, and that your work was helping advance technological superiority?