Well, what exactly has Blender to offer that would have commercial studios turn their backs to the software solution they used for years?
Is Blender better than Maya / 3ds max / etc.?
Arguable. Blender is not perfect - there, I said it. It has its shortcomings and flaws like any other 3D app. As already mentioned the renderer has been a problem child for years and Cycles is only slowly maturing into a feature-complete and production ready solution. Overall Blender has more and more become the “Jack of all trades, master of none” - and with no area of the software that excels in a special way, where could the impetus to change come from?
But Blender is free!
Yeah. So what? If you work commercially, software costs are business expenses anyway. And if you are established in business you already have invested larger amounts of money into commercial software and plugins. So the argument of software costs will mostly attract start-ups or small studios / freelancers. Which brings us to another problem:
Blender in a pipeline?
IMHO one of the biggest problems. I don’t see Blender in a (mixed) production pipeline, as it doesn’t play well enough with others. This poses trouble for the small freelancer mentioned above, as he/she might end up with not being able to deliver/receive data. Many importers / exporters (even for industry standard formats) in Blender are still in development, unfinished or just not robust enough. If Blender wants to play amongst the big guys, it first has to learn to play with the big guys.
With all that said, why would any studio want to retrain their entire personnel to Blender? As already stated, start-ups might be a different story.