I agree completely, but I am quite certain that the police liveries will not be altered by Rockstar - as much as I'd like to see them in proper LSPD markings.
We can only wait for the PC version to be released and have all of the many inconsistencies with GTA V corrected using mods.
I think the best police vehicles to date are the LCPD cruisers from GTA IV. Why didn't the same amount of detail and accuracy go into the LSPD fleet?
You are right in that regard with the LCPD cruisers except when they cross the Humboldt into New Alderney, but that is another discussion. If we are taking purely about liveries they are miles better then the LSPD police vehicles (bar the Vapid Stanier 2nd generation). After seeing the new trailer it seems that the hideous livery is here to stay.