Long ago one of the triggers for an expansion of copyright law was someone doing a clever job skirting it, who came up against a judge who wanted to put a stop to whatever he was doing. The only problem was according to earlier precedents the person wasn't actually copying anything. (Sorry - I forget the exact facts - it was a long time ago.) Anyway, the judge then had an epiphany - when the content was being played / transmitted or whatever it was, the bits were beginning copied on the bus lines.
That got leapt on by the copyright owners to mean they could control any copy, no matter how transient - and so the distinction between making a copy and transmission disappeared. If you copied something you not only had to have the legal right to have copies on on the source and destination (which this guy did) - you have to have the legal right own the "copy" on the transmission method.
The judge got his conviction of course, but all computer programmers watching on recoiled in horror. Later came the DCMA, which was actually an improvement on that situation that decision created.
Requiring a specific update to the law in order to encompass new devices - which probably have different features and usage patterns - is worth the inconvenience to lawmakers. Sometimes an "automatic extension" of a law to new-but-related devices is appropriate, but many times it will not be and I'd rather err on the side of less law.