The original transition (and release of extra frequencies) was a delicate and painful process with lots of involved parties who had to spend lots of money to make it happen. Politically speaking, it could only happen if everyone involved saw some actual benefit from the change.

If you got into a time machine and tried your plan two decades ago, the conversations would have gone something like this:

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Government: "Hey broadcaster, we need you to throw out and upgrade all your broadcast equipment that's working just fine today."

Broadcaster: "Why?"

Government: "So we can auction off some of the broadcast channel bandwidth."

Broadcaster: "Why else?"

Government: "That's really it."

Broadcaster: "How about instead, I take a little bit of that money you're asking me to spend, and give it to your political opponent's campaign?"

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Government: "Hey citizens, we need you to buy a new TV or buy an adapter for your current TV that's currently working just fine."

Citizen: "Why?"

Government: "So we can auction off some of the broadcast channel bandwidth."

Citizen: "Why else?"

Government: "That's really it."

Citizen: "How about instead, I vote for the opposition candidate who says he'll let me keep my TV and my money?"

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We're able to juggle broadcast frequencies more easily after the transition. Not only did we shrink the broadcast frequency range at the time of transition, we did it again about ten years ago with far less pain.

https://en.wikipedia.org/wiki/2008_United_States_wireless_sp...

https://en.wikipedia.org/wiki/2016_United_States_wireless_sp...

TL;DR: 480i would have been an absolute non-starter.

Federal Communications Commission scraps limit on broadcast TV ownership