This is hardly surprising or news. In short: WoW was the first wildly-successful MMO to make it out there, hence it's the one everyone wants to try to clone. One must remember that game development is a business, and all businesses want to be successful. In earlier times it was Everquest that was the "standard setter," and before then, Ultima Online. And later, once WoW's gone the way of its predecessors, whatever is top dog THEN will be the one all others will be held up to.
This applies to ALL genres in gaming, not just MMOs: the FPS we compare others to is whatever is most popular, so we've seen shifts from referring to FPSes as "Doom-clone" in the mid-90s, to then comparing games to Quake, then Half-Life, Unreal Tournament, Halo, and most recently Call of Duty.
However, I'm not quite sure if The Old Republic will actually be truly competing with WoW: in some ways WoW's already hit its peak: that happened around two years ago, when it FIRST hit 12 million subscribers. (I notice that the Google ad right now mentions this number) Since then it's drifted downward, but has lifted back up to 12 million thanks to Cataclysm's release. A look over the history of popular MMOs show they start with a strong growth slope, followed by a peak, with some "leveling off," followed by a more gradual decline, at 1/3rd to 2/3rd of the rate they climbed. Hence, as WoW originally grew at around 3 million a year, (going from 0-12 million in about four years) it's going to start declining at around 1-2 million users a year.
TOR won't be instantly a "big player," at least if Bioware is to succeed: all MMOs that saw an initial hyper-growth period with a fraction of a million subscribers in the first month all peaked more or less instantly, which meant folding within a year. (remember, an MMO's peak comes almost always around 20-30% of its lifespan, so a peak at 1 month means a 3-5-month life) Assuming that TOR is to grow into the multi-millions range, it's going to do it gradually, taking years. If it follows WoW's pattern, even if it DOESN'T peak as high, it won't be until late 2015, by which WoW will have dropped to around 4.5 million users. (I predict WoW to shut their doors entirely between 2018-2020)
So perhaps, trying to model after WoW to make the "next big thing" might NOT be a good idea, since if it IS the next big thing, WoW won't be really around in the same commanding position. However, I'll admit the other side of the coin: a game has to START with success... And right now, we're in the year 2011, where WoW has been king for about 6 years now, ever since it bumped off Lineage. It'll be interesting to see what the future landscape of MMOs looks like in a few years from now.