Use of others' cultural features can be stupid inasmuch as it is misuse, abuse, or conning people. Just because something is stupid doesn't mean it should be banned or stopped. People are free to be stupid in the cases where it actually is (and no, I don't think it always is). On the other hand, if we are in control of such stupidity, then we are also free to try to stop it. So if we partly own a corporation or are part of an organization or other institution and such entity is misusing, abusing, or conning people, then we are free to voice our opinion about it and also to put our two cents in to try to stop it. Personally, I probably wouldn't make such issues a priority unless the specific issue has high impact or risk to other people.
Regarding cultural appropriation, that may be somewhat different in that it requires an oppressed group whose culture "owns" a feature which then gets appropriated by a larger oppressive culture. I think this also has to be looked at in terms of freedom to be stupid and what freedoms we have not to be stupid. We should also consider to what extent appropriation of said features impact persons being oppressed. I suppose if it is economically impacting them, it is systemic, and it is a recurring issue, extensive through time, then inasmuch as we have freedom to do something about it, we should. However, I do wonder if the greater problem is the oppression itself and if the cultural appropriation is only incidental to that.
Now, as far as the op, yoga probably has been "appropriated" in the sense that a lot of non-Hindus are practicing it, but that is not to say it carries the negative connotation of "cultural appropriation" as described above. I think that today in the US (and Canada) Hindus have a lot of freedom. Many choose professional careers over being yoga instructors and there is not a lot of discrimination except at the upper most tiers (being a corporate executive) for these people. So I think the impact of this issue is very low. The benefit, too, is high, in that yoga is very healthy for all of society. Now, could a yoga class teach something about the cultural originators of the concept? Yes and education in that regard would probably have some value. It just does not seem like a priority to me based on the cost-benefit I have described.
Though I could be wrong.