The Rivian has a 4.5 foot bed[0] and the F-150 Lightning has a 5.5 foot bed[1]. I don't think it's fair to call Cybertruck a novelty item based on its capabilities, especially compared to its competition.
(Of course there are completely legitimate downsides of Cybertruck - for example, with the sloped bed sides, it won't be able to tow a fifth wheel trailer. But that is a capability the vast majority of truck owners don't use.)
0: https://rivian.com/r1t (Dimensions → Storage)
1: https://media.ford.com/content/dam/fordmedia/North%20America...
(Of course there are completely legitimate downsides of Cybertruck - for example, with the sloped bed sides, it won't be able to tow a fifth wheel trailer. But that is a capability the vast majority of truck owners don't use.)