Not an expert, but my sense is that it's at least in part due to widespread cheap/commodity consumer cameras becoming a thing between the planning of Curiosity

Not an expert, but my sense is that it's at least in part due to widespread cheap/commodity consumer cameras becoming a thing between the planning of Curiosity and the planning of Perseverance. In earlier missions, cameras were usually big and bulky and designed specifically for their respective research functions, and if you're designing something from scratch, you design it to maximize research utility first, and sending home cool videos is probably a secondary consideration. So I'm not sure many of these could do video (because it's probably not that useful for studying rocks that don't move), and a lot of them didn't even capture a spectrum range exactly matching the visible range (I think some of them included parts of the near-IR range, etc.), so a lot of the images from earlier missions that were released to the public had color that was faked/recreated in post-processing. I think the new rovers still have these specialty cameras, but now that there are decently good mass-market cameras from the cellphone/consumer-electronics industry that cost $5 apiece and weigh a couple of grams, it seems like there's no reason not to throw a few of those onboard as well. I would speculate, also, that video compression might be part of the story. Processors on these vehicles tend to be specialized radiation-hardened chips that are modified versions of several-generations-old general-purpose processors. I think Curiosity's was a rad-hardened 200MHz PowerPC chip, for example. I would bet that those chips just weren't up to the task of compressing high-quality video enough to make it practical to send, given the bandwidth constraints of transmitting from Mars to Earth.