You have a point, but let's put it this way - the first home console version of Street Fighter 2 did not have a training mode, which Capcom quickly realized was an oversight and corrected IIRC when SSF2 TCE was released; it's been in every SF title since and has been appreciated by both hardcore and casual players* for the opportunity to develop new strategies. Now a 2D fighter and a 3D TPS are very different, but both require comprehension of advanced tactics to be successful. I suggest giving players access to a training mode would reduce the amount of PUG foolishness and cut down on amateur/veteran players being burdened with teammates (like me at times
) who have to be revived every 5 seconds.
BTW soloing does work somewhat effectively for this, although it's not that efficient to have to drag garbage weapons through 11 waves just to confirm you don't want to use them (unless unlocking achievements). I really think a training mode - at least a firing range - should be added to ME:A MP. Though I'm hardly a dev so I can't say how much that would tie up the game engine.
*I do not appreciate how recent versions of SF have featured a training mode focused on beating the crap out of yours truly. Capcom will be hearing from my lawyer as soon as 34,768 more people contribute to the Saikyo Dojo Legal Defense Foundation and Ramen Cart. Tax deductible.
In fighting games, the mechanics of the game are extremely deep and those modes are for learning the frames, properties, and damage of different moves and learning combos. With a game like ME, the difficulty is made to scale gradually (exceptions like Garrus' ME2 recruitment and Grissom Academy) as the player is more in tune with the gameplay.
I don't necessarily disagree with you as I see where you're coming from, but fighting games (the ones that matter) are on a whole 'nother level of depth.