Just like many things in our society, Yoga's evolution has started to happen quicker and quicker in recent years. Yoga is everywhere now. Yoga is being mass marketed and used in popular advertising from clothing to yogurt and everything in between. You can find Dog Yoga, Acrobat Yoga, etc.
Is it a good thing or a bad thing?
I do think that Yoga is diluted in many of these off-shoots. Many people think Yoga is purely a physical practice and many teachers (myself included) have a predominant focus on the physical aspects in class. Many people don't know and may never know of the deeper practices and benefits of the other Yoga practices such as pranayama (breath control), pratyahara (sensory withdrawl), etc.
On the flip side, the general dilution is what has made Yoga accessible to others. Some people only want the physical benefits of Yoga (which are great). Some people would be turned off by an overly philosophical class. And the vast variety of asana (physical Yoga) classes out there, means that Yoga has the opportunity to touch more people. My classes are very gentle and have lots of modifications for those that need them. Other teacher's classes are more vigorous. Some classes have chanting. Some have meditation. In this way, people can explore and find the Yoga style that works best for them and reach out to explore Yoga's non-physical aspects if they are drawn to.
For me, I teach a predominantly physical class, with some breath awareness and a philosophical reading. But for my personal practice, I am drawn to the more spiritual aspects of Yoga.
I think Alice Walton discusses this issue great in her article: The Great Yoga Debate