First, let's start with the argument that the Sith Inquisitor and Jedi Consular are lacking in creativity and that an opportunity was missed. Indeed, you could argue that something other than two more force user classes should have been chosen because, well, it's a little uninspired. Although, I'm not really sure what other class archetypes would've been worth pursuing in their stead.
A pet class may be on some of your minds, and that's perfectly reasonable -- except that every Star Wars: The Old Republic class has pets. Companions pretty much ruled out pets to begin with, which is why I never really expected that kind of class to happen. So now we're left with some kind of engineering class that deploys turrets or gadgets of some variety. That's kind of like a pet class, though, and really just doesn't sound fun unless you're able to controls robots... hm.
I did think some kind of martial artist was potentially in the wings. In fact, a kung-fu space hero seemed like a pretty cool concept. It does deviate from the heroic archetypes BioWare has stuck closely to so far, however.
And maybe that's the problem. Maybe sticking so close to these core classes is creating a game that doesn't really offer anything to non-jedi players and the hardest of hardcore Star Wars fans. Sure, BioWare is catering to people who want to be like Han Solo or Boba Fett, but what about beyond that?
The risk with adding two additional Jedi and Sith classes is that there won't be enough variety. SWTOR only has four classes per side (but really it's only four total, as they mirror each other to a good degree) so there's a finite degree of difference we're going to see from player to player. How many Bounty Hunters and Jedi do I play with before they all start looking alike?
Of course, on the other hand, maybe these are all the classes SWTOR really needs at launch.
The opposing side of the argument is that, "Hey, these classes are pretty awesome!" While it's true that extra Jedi and Sith classes mean more players running around with lightsabers, it also means more variety between each force wielder you encounter. Is this new guy "Palpagreen" a Sith Warrior or Inquistor and what build?
Sticking to their strength is a smart move, as it allows BioWare to evoke a maximum amount of nostalgia. This is after all the KOTOR MMO we're dealing with and the Consular was very much a part of that game. Let's not forget, however, that we're dealing with a different beast altogether here. That is to say, as a support class the new Consular is going to fill a vital group role that just about every MMO requires: healer.
Does that mean SWTOR won't be any different than your typical sword 'n board MMO? Well, yeah I guess there's a small chance. The game was going to have at least a few things in common with other MMOs in the industry. Sure, it would've been nice if the class structure deviated from the well-trodden MMO archetype path, but there's already plenty about the game that's different from the norm. Plus, there's likely so much more we don't know.
Thankfully, there are always expansions. Since class stories are such a core aspects of what makes SWTOR tick, a new expansion is likely to at least bring in some new classes, too. And it's entirely possible that these class picks are "safe" for that very reason: expansions. Whether it's a matter of budget, time or design issues the fact of the matter is that creating fun classes is quite the challenging task. I've no doubt that much hair pulling has already occurred over these first ten classes already, let alone for future -- less "safe" -- additions to the game.