I agree that government succeeds when it is well managed, but you cannot rationally expect to defund govt and magically expect it to be better managed.
I am not a fan of the additional net deficit as a result of this tax bill; I think it could/should have been revenue neutral.
I think the “not well managed” argument comes from insincere people that just want lower taxes and will come up with any reason or excuse to get there.
Milton Friedman made the point, with which I agree, that government cannot be made overly efficient, because it will never pay enough to hire good managers that would make it so, and even if it did, competing political interests and special interests would still make it impossible to make every decision a sound one made for sound reasons alone.
Ergo, the only logical position to hold is to make government as small as is possible. If losing money to efficiency is inevitable, then the solution is to give them as little as possible to lose.