In fact, I cought myself thinking the same thing myself and I want to make a mod out of it, but with only one condition if you agree. Imperial units only buildable on certain Imperial planets and only in era 1 and 2.
In Era 1 it makes sense somewhat as they still had plenty of Imperial gear left from when Palpatine funded them, and in Era 2 because Thrawn is the leader and he would definitely support his empire.
After that Palpatine just did not care, and the others never knew about it until... well... you know. But by that moment they did not used the not too well aged Imperial gear.
And don't even count to have SSDs. It was not the Hand's style.
Should I start now or give you instructions on how to do that yourself so you can have it to your own taste?