Uh, because all remakes are ****. Excuse the language, but there are NO OTHER words in any language which adequately convey my opinion on this matter. No original movie I know of was improved by a sequel or remake.
If you want to watch Bullit, go obtain a copy of the original
Besides, if they did remake Bullit, they would star Vin Diesel, who should be barred forever from ever acting in any movie