This was made possible because of the ability to send microwaves across the country, giving many more people access. As a result the FCC granted 500 new stations the ability to broadcast on the network. It was called, "'The golden' age of technology."
This is a big to deal to Americans as it was back then because it is something that is now almost considered standard and almost a social status of if you've seen the latest episodes of a certain show. It is also a way to receive news and broadcast emergencies quickly and thoroughly, such as forest fires, inclement weather and even accidents around where you're located for travel reasons.
He delivered this speech because Richard M. Nixon was accused of profiting off of a slush fund. Nixon denied this but did admit to the acceptance of a gift from on of his political supporters. This was probably done to make it look like he wasn't trying to deny everything and come off as suspicious. He was able to keep his place on the republican ticket by doing that speech.
Eisenhower won the election in 1952 and Republicans barely captured congress.