But they were clearly widespread enough to have sockets in 1st class.
I admit, the plug for every seat concept would have been overkill at the time, however having a few scattered throughout standard would have made sense at the time from a passenger comfort perspective.
I assume the power sockets were geared more towards laptop users. As has been said, in 2008 most phones were feature phones and people weren't glued to them 24/7 as the screens weren't great for media consumption (nor was 3G capable of streaming very well, especially on trains due to the massive limitations of the technology compared to how 4G and 5G works).
It would have been nice to have power throughout, and I am sure it will come - albeit almost certainly ONLY USB ports, not 240v plug sockets. Meanwhile, first class will probably retain the mains sockets and maybe USB as well. Who knows?
That's no excuse for not having things such as seat back tables though. There was undoubtedly a lack of consideration for the needs of longer distance passengers in that respect.
Also, we've had sockets on trains for a lot longer than since 2008. It would have been worthwhile putting a few in standard even then to keep up with the obvious trends.
I got the argument about the fear of tables getting people all tangled up when travelling in the core. I am not sure it turned out to be such a problem after all, but there was logic to it. In the core, the train is more like a tube train and having someone on the aisle seat setup with a laptop on a table (potentially plugged in too!) could make it hard for the person with the window seat to get out.
It would certainly be easier to retrofit tables than wire in power sockets, but the DfT has made it pretty clear that it has no intention of retrofitting anything to the first of the 700s built - meaning it is a complete lottery as to what you'll get.
Personally, I'd be happy with a very small table that is enough for a cup of coffee or soft drink, rather like the 365 tables. Not really big enough for a laptop, but a laptop likely won't fully open anyway.