I see your point, and raise you another.
With rumors of the Fold 8 being a wider passport-size dimension, it reminds me of comparing bi-fold wallets to tri-fold wallets. Both types of wallets are still in circulation and you choose between a wider, slimmer wallet versus a thicker but narrower one. Similarly, the TriFold phone will be thicker but narrower in your pocket than the future Fold 8.
I don't think the TriFold will be to unwieldy because it is actually still thinner than all previous Fold models, except the 6 and 7. Weight, on the other hand, will be noticeably heavier, but again comparable to my heaviest phones with screen protectors and case. As great as the Fold 7 is, I still sometimes wish for an even larger inner screen on my Fold 6 and that is where the TriFold comes in. The TriFold doesn't collapse down to an "average phone" because it's practically the same as a Fold 7 with an additional screen layer, and nobody asserts that the Fold 7 is a poor phone.
Yes, the extra folding motion is an additional step when opening and closing the TriFold, but I still much prefer that to carrying an additional tablet that brings added weight, additional power needs, potential extra data plan, and now also a backpack or messenger bag so I don't have to keep holding the tablet (since it definitely won't fit in my pocket). Not only that but, unless you have the more expensive Tandem OLED iPad Pros, I found my last M2 11-inch iPad Pro's display couldn't match the black levels and quality of my Fold 4 at the time.
I am fully prepared, mentally and financially, for [up to] a $3000 U.S. TriFold and am willing to pay for the convenience of that expansive display. I plan to keep it at least two years so the price isn't too much more compared to annual upgrades. On top of that, I'll be able to trade-in my current Fold 6 and there may be additional pre-order promotions too. I wish it had S Pen support for such a large foldable, but oh well. I do have concerns about longterm durability and the lack of Samsung Care+ option in other territories. I am hoping the U.S. release will still have a protection plan available or I may have to look into SquareTrade/Asurion.