Laptop ban on aircraft

The UK has joined forces with the US in order to introduce a ban on laptops and any other large electronic devices in handheld luggage on flights directly from Muslim-majority cities/countries. They claim the move is a counterterrorism one because of attacks on airports (Brussels and Istanbul), along with facts like the downed jet from Russia that took off from Egypt in 2015 or the attempt in Somalia to down a jet in 2016.
However, it is worth noting at this point that the Lockerbie bombing in 1988 did not take off from any of the airports affected by the announced ban. It had originally taken off from Frankfurt in Germany, and then had a stopover in London Heathrow. It was, of course, a bomb that had been concealed in an electrical device but it was in the hold and not a part of carry-on luggage.
If such a ban was to be announced worldwide it would seem to be fairer, because, at the moment, it appears to be discriminatory. Turkey has already said that this ban is wrong and should be lifted immediately. Many other countries affected by this will probably take similar approaches. If you take Lockerbie as an example, then it is instantly clear that a ban on the carry-on luggage would have absolutely no effect on the outcome. It would still explode and have deadly effects just like it did in 1988.
It is doing very little to uphold the illusion that we are not discriminating against Muslims in general. Saying that we are doing this because of national security means that we, as a country, are making a statement that these Muslim majority countries are not safe.
Looking back at history, it would appear that the threat is greater around the United States, Europe, or indeed the United Kingdom itself. It leaves you wondering whether we are placing the ban in the appropriate places.
Phones are exempt from this ban, which is a very strange thing to do as a phone can do pretty much anything a computer can do. True, you would not be able to hide the same amount of explosives inside one, but, as shown in history, this could be concealed in the hold. Anyway, even a small explosion on an aircraft could prove to be deadly.
Should electronic devices be completely banned on all aeroplanes as a preventative measure? Worth a thought.