I don't think I'm following your debate very well... But from what I understand, you're saying (basically) that, "Abilities don't change a Pokemon," and, "Pokemon are constantly changing so we would have to as well." Correct?
Well for the first statement, I don't see how abilities couldn't
not change an individual Pokemon (TRIPLE NEGATIVE WHOOO). Take Bronzong for example. Sure, it has all the great defensive tools it needs with either ability, like awesome typing and a good movepool, but its list of checks and counters changes drastically when you switch its ability from Levitate to Heatproof. Although they are the same Pokemon, they are played differently.
Same applies for Blaziken, Chandelure, and Breloom. Even though they are the same Pokemon with their alternate abilities, they function quite differently than they do with their other abilities. SB Blaziken abuses Protect and Swords Dance, ST Chandelure can decimate many threats through revenge trapping, and Techniloom uses an entirely different movepool sans Spore. They are the same Pokemon through aesthetics, BST, and movepool, but their abilities allow them to function in an entirely different manner. So Blaze Blaziken and SB Blaziken are
not the same Pokemon competitively. And that's what Smogon aims to do: battle Pokemon competitively.
In terms of your second statement, the world of Pokemon may be changing more rapidly than ever through the Dream World, but we can predict those changes. We know of all possible Dream World abilities and can discuss them as we are now. And if new movesets come about, we would deal with them through Suspect Rounds. I don't see how the Dream World complicates anything in that regard. Smogon is still going to run Suspect Rounds no matter which venue we choose, so I can't see it harming us further.
On the whole, I respect your ideas a lot and do see a lot of validity in them. As we can tell from the poll, Smogon seems to be split quite evenly on which option they prefer. It is quite the pickle we are in.
Go read
this, por favor.