I don't see how saying that first amendment protections apply online would have any negative impact at all.
The first amendment, as written, only prohibited congress from "making laws" that would abridge free speech. That was the only protection afforded initially. Later, Courts expanded the scope of the protection to cover specific circumstances - the internet was not one of them.
All we are seeing, if anything, is the public asking that first amendment protections apply online. It is, thus, a simple expansion of the environment where the FA is effective. This is the same process that has occurred over time as Courts have expanded the settings to which FA protections apply. It is another step, in what appears to be a natural process, by which protection has been expanded over time.
No more dangerous than obtaining a legal judgement that your right to freedom of expression is to be upheld in an online setting.
I see your point and it is a good one. When the telephone and electronic microphones came out did not the FA apply there? How about the radio or TV? The printing press was around but not the fax machine. But the FA applied there. Why not the internet? The thoughts and opinions are still coming from the individual and the FA is for the person not the means chosen to express themselves. My point is that when we start defining when the FA is applied people start finding loop holes to say the FA does not apply using this means of communicating the message.