It would a frivolous waste of money we dont have to fix something thats not broken.
Ah but it is broken. For a start there is no agreed upon standard for several of the units e.g. fluid ounce for which the Imperial unit is not the same as the US unit which is then further compounded by the fact that there are 20 fluid ounces in a UK pint and only 16 in a US pint. As such it is a completely broken unit system you not only have to memorize an insane number of relationships between units you even have to remember whose imperial-based unit scheme you are using.
However, what makes it s truly broken unit system is that it uses the unit pound for both mass and weight. Yes there have been "hacks" of the system to bring them inline with physical reality so you have the "avoirdupois pound" meaning a mass and the "pound" meaning force. However this means that the units are not clear: when you say "pound" do you mean force or mass? If you need to tweak your unit system to make it consistent with physics that's not really a good sign is it?
If that's still not enough to convince you that there is a problem then consider that there are only three countries in the world still using the old imperial-based system: Liberia, Burma and the USA. There are not many things that practically the entire planet agree upon but apparent metric units is one of them and it is not without good reason!