I'm not saying I wouldn't take it if it's there, but if that was the ONLY upgrade for the Pixel 4 or 5, then no I wouldn't upgrade. But that won't happen, because like me, no one would buy it simply for a RAM upgrade. It'll have a newer processor, some software options that won't be available on previous models, camera improvements, etc.
But if you recall, a few years back one OEM put more RAM in their offering, but then aggressively limited the number of apps that could stay open (I'm thinking it was OnePlus). That was a seriously dumb move, either you keep the same RAM and limit the number of apps, or increase the amount of RAM and let the Android OS determine how many apps it can run. So if they're just putting X amount of RAM in to pad the spec sheet, then it's all about bragging rights and to push the maybe buyers into the affirmative camp aka "Everything else is the same but it's got more RAM!" My honest opinion, if it runs fluidly, I wouldn't care how much RAM it has. At some point it'll need to be upgraded anyways, so I'll upgrade.
Now here's a question for the ones reading. A lot of people are complaining about Google shortchanging us on the amount of RAM. Some of it's coming from people who upgrade yearly or even more often, so "future proofing" shouldn't be a worry for them. Some of it's coming from people who are on much older phones, as far back as the Nexus 5, which had 2GB of RAM. So if they're worried about it, why didn't they upgrade sooner? That's a 5 year old phone, and there were 3 other models of newer and more affordable Nexus phones available. So if they're able to make it to now with 2GB of RAM, I'd imagine 4GB and the newer processors should hold them over ok until their next upgrade.