That's why for me the Series X day one was a no brainer. I have no interest in buying any of the "next gen games" at launch, only The Medium really interests me and it'll be in GP so great. AC not bothered, COD looks a backward step from MW, Dirt 5 i like the focus on features, but their games have gone downhill for years and FH4 will be better, especially with the upgrade.
I just can't wait to get hold of the upgraded hardware for the quality of life improvements it will provide to my gaming life in general for the hundreds of games i have in my library, many of which i still haven't touched, including many big hitters like RDR2. The performance leap is astronomical, especially the CPU and obviously SSD. Not long ago i played The Outer Worlds vis GP, not much of an RPG player at all but loved it. It had plenty of depth but not all consuming and needing 100's of hours like some RPG's can be, and put me off. The main negative, like so many games, was loading times especially when selecting fast travel locations. I can't wait to experience games like that with next to zero load times..real game changer. Also things like FH4 loading to get in game, between races, even to get refunded credits for failed auction attempts etc all take too long. This will all be a thing of the past.
For players, often older generation like many of us on here with jobs and kids etc, gaming time is often limited so the more time playing and less loading is all the better.
As for whether worth jumping in day one, that's obviously a personal decision based on a number of factors. Nobody can answer that question for anyone else. For me as above Xbox no brainer because i have hundreds of games in the ecosystem and play on it most days. Yes it'll be cheaper in a year maybe, but the benefits i'll have for that year easily trump the potential saving i might get. Also, traditionally and especially Sony side, later in the generation you'd often get console and game bundles, but with game pass that's rendered irrelevant anyway. Also on that note, if you waited a year to save maybe £50 you might miss out on a number of 3rd party titles that are in GP and the leave during that time, so in reality losing out. GP offers a completely new dynamic this gen and without question the best bargain gaming has ever seen, especially the prices and deals it can be had for. Even after the one off ultra promos you can then get 3 month codes working out about £8/month.
Personally the PS5 isn't something i have any desire to get day one as i'm more invested in Xbox, so will carry on with my slim for now and upgrade that side when i know for sure my current games, again vast and many unplayed, will work BC, alsong with my PSVR and games for that, what benefits there may be etc. I don't trust anything Sony have "hinted" at re BC up to this point. Will probably wait until it either drops, or drops with a bundle worth having, or ideally they increase the SSD size, then i'll most likely bite.