The reason for Sony to bring out the PS5 Pro is for 60 fps GTA VI. That's all really, and it's probably enough of a reason.
As I said many times, MS should follow a year later with something 25% better, but announce the crap out of it so Xbox fans wait rather than flee for PS5 Pro. It more or less worked for X1 Pro vs. PS4 Pro.
Sometimes in these discussion we forget that on Series consoles you can still play Elden Ring, BG3, Hogwart's Legacy, Resident Evil series, Cyberpunk 2077 etc... a lot of big titles. The Xbox vs. Sony 1st party can be debated, but there's not much difference in 3rd party lineups really. Sure there's a few things like FFXVI, but for the most part the Series consoles have a lot of great games to play.
I've been thinking about it more and have come to the conclusion that for the beginning of this generation (and maybe the whole generation) MS kind of has to play Sony's game as it relates to 3rd party and hardware utilization, but as the 40 studios get cranking, MS having more powerful hardware for 1st party can make more sense over time. So when 1st party output is low, like 2022 where almost nothing is released, you're not going to be able showcase better hardware even if you make it, because 3rd parties aren't really going to bother using more compute or memory when PS5 is the lead platform for practically every game. But as 1st party output increases to 6+ AAA budget games per year over time, then MS can use 1st party games to really showcase new hardware. GTA VI can more or less look the same between MS/Sony platforms, but Gears 6, Fable, State of Decay 3 etc... could really showcase new hardware that MS brings out if they decide to keep up in the tech arms race with Sony.
It all boils down to the games. They need to have the showcase titles that make the new hardware shine, if they're going to bother bringing it out.