Having the government decided which technologies can be used might have had some benefits here but it seems like there would be a lot less work on making technologies better and a lot more work on lobbying if that were the case.
While I don't think the mandate would have been a good idea, I don't think you can use the US as a case for 'making the technologies better'.
We're way behind everybody else...
Mandates worked for TV standards (original standard def). Then when high def came around, everyone was lobbying for their own formats with too many official formats.
The government could have just mandated that the industry had to settle on a single standard (without the government needing to specify which technology to use).