If you're going M20 Utility, you don't tech racks beforehand because you get a bazooka on the LT to support the Utility Car, and you need munitions to hand for smoke and possibly skirts.
If you're going M15 AAHT, you don't tech racks because you can tech a BAR on the Captain directly.
You don't rush the Stuart unless you're playing Mechanized because it's not a shock unit.
Once you've taken all that munition expenditure into account, you'd have the muni left for, what, one BAR? It seems crazy to delay your tech for that.
Here again what is the point? With your proposal everyone will be forced to rush the stuart since every OKW Lvs is going to hit the field faster. I mean it is not like there were no reasons for the balance team to delay the Luch behind a 60 second build.