But how will the PTB make any money off things that work and can be cheaply (relative) produced and maintained?
Make lots of them. (margin or volume)
In that sense, weapons procurement reminds me of Pharma. The latest newest Improved, lemon scented version is always best...or will be once the bugs are worked out.
I'm all for new tech, just prove the prototypes, work out the bugs, and
then take it to production. We would be fools at this point to not assume our enemies are reading the plans for them as we build the jigs, tools, and dies to produce them.
For any weapon that has a role in the battle space, don't discard it until you can replace it with its equal or better to fill that role.
If someone thinks a role is obsolete (the job is no longer there to be done) someone somewhere will exploit that weakness, even if the means are considered antiquated. Pick a war where horses (or other beasts of burden: pack mules, water buffalo, etc.) have not been used, for instance.

For all our advances, the infantry still walk, when they aren't keeping too low to not do so.