I find that overly punitive toward Dex. Without a hit or damage bonus a 20 Dex / 8 Str rogue would...suck. Majorly. You'd need massive class bonuses to compensate.
I think that that is a reason why D&D has the finesse mechanic: to make low-strength martial characters effective.
But that suggestion was intended towards the original idea of the thread, which was to prevent precisely what you are talking about: a martial character completely dumping one of Strength and Dex, and maxing the other rather than having a balance of the two.
How is Finesse more "useful" than Versatile? You can't actually do anything with it, it just allows a different sort of build to wield it. The game could have been written so that all the non-Finesse weapons had a property called "Awkward" ("Cannot use Dexterity as your attack stat") and there would be zero impact on the game.
So Finesse doesn't actually have any "value" to those who use it. Not like Reach or Light or even Versatile, however rarely the last one is actually utilized. (I will agree it would be nice if there were more incentives to occasionally go 2H, besides the +1 damage.)
I believe that they were referring to the value of Finesse in terms of it enabling the otherwise more advantageous Dex-build instead of having to put ability points in Strength in order to use a d8 weapon.
No. Making damage creep up is not going to solve anything. And the game does not need a Katana. Or any more weapons, really.
Agreed. a two-handed Finesse weapon is a pretty weird concept to start with. Arming sword seems covered by Longsword already. (And I wouldn't have thought of arming swords as commonly dual-wielded either, so I'd be unsure of giving them the Light property.)
I wouldn't combine Dexterity and Strength-- I think it would be better to combine Strength and Constitution. Both stats are generally about being bigger and more muscly.
I really think the idea of a character who would be high on strength and low on constitution or visa-versa would be quite an unusual niche-- any character created organically is going to excel or struggle with both.
Its a little odd. Best example that I could come up with would be a body-builder-like character, capable of a lot of power, but not good at sustained effort. But they would also need to incorporate the general sickliness and lack of ability to fight off disease and poisons etc.
As you say, its a bit of a struggle.
But a high-dexterity, low muscle character is considerably more common of a notion.
I actually find it really hard to come up with an example of a high-dex, low-str character for threads like this.
High Str and Dex characters are fairly common and recognisable, from Conan to Bruce Lee.
Low-str, high-dex would be someone like Bilbo Baggins perhaps? But hobbits are described as quite athletic. Need an example of someone graceful and balanced but unathletic. A couch-potato with quick hands from playing console games perhaps?

Likewise, athletic-but clumsy is also a tricky combination to think of an example.