The transhumanist philosophy was transcendental. Man, armed with innovative genius and deep technological knowledge, could one day remake himself and transcend his limitations. It wasn't so much a "philosophy" as a prediction of an inevitable and obvious future, which they were simply impatient to reach. Freedom from all biological, physical, intellectual constraints!
Today, people understand that technology isn't just a tool, it's a weapon. Corporations want to corral people into virtual worlds they control, and governments want perfect surveillance and infallible enforcement of all laws, and soon social rules. Your brain implant will have NSA/China backdoors, regular 0-days "observed in the wild" (sorry, no refunds), or will crash occasionally because the QA team got laid off.
Smart technologists today can see that virtual reality (which is indissociable with brain implants and most other transhumanist tech except perhaps nanobots) just means far deeper corporate/elite control over people's psyches. Read "The Rise of Virtual Reality" by Anthony Napoleon. The replacement of "real reality" (governed by the laws of nature) with a reality fully governed by other humans (and their flaws). It's very hard to get giddy and impatient about that future.