Wait! What?
 

"The new rules will also apply to aircraft powered by alternative energy sources, such as electric aircraft."

If this measure is aimed at reducing CO2 emissions generated by lifting the weight of (unneeded?) fuel reserves, then why apply it to electric planes? A few extra electrons aren't going to weigh that much.

A cynic might suggest this was driven by a political need to enable otherwise "fuel"-critical electric aircraft to operate at all, as they will be so desperately limited in endurance and will often struggle to manage sensible "fuel" reserves, and dressed up in greenwashery to make the fudge less obvious...

On the rare occasion I ever felt compelled to justify carrying extra fuel on the paperwork a (some FOs got terribly excited if you didn't) I simply wrote "airmanship". That tended to get them even more excited as this was a swearword in my last company and magenta-line/unthinkingly SOP-enslaved FOs thought it verging on subversive.
It was never questioned.

I had a brief read of the new rules when they came out then carried on as normal (target but extra if there is an extra risk or hazard and everyday common sense). Still waiting for TAFs that report cloud at 150ft too.

It is not only weather and traffic will get you. You arrive somewhere with forty minutes in tanks and you get a stuck gear, stuck leading edges, asymmetric flaps or whatever that forty minutes is going to disappear faster that you can say goodbye. It will be landing coming ready or not. And if that closes the runway and there is a string of airplanes behind you on minimum fuel that is their bad luck. They can go find a paddock.

Unfortunately, the people in airport operations aren't necessarily as clued up on these rules as airline ops and flight crew. I have witnessed a situation when a Cat 1 destination went out of limits (un-forecast) and ATC announced that three of the possible four available alternates in the country were not accepting diversions. Until pressure was applied through ATC to bang some heads together at these airports, none of the three aircraft holding had a diversion available. Airport ops seem to base their diversion availability on whether they have enough handling staff, steps, chocks etc rather than the fuel planning rule that simply requires a strip of concrete and some kind of instrument approach.

Although there are a lot of runways available in the UK, there is a creeping tendency for airports to declare themselves unable to take diversions or even more vague they are now saying "may not be able to accept diversions" and this make planning around minimum fuel strategies even more complex. This can be a problem early morning with widespread fog and when many airfields don't produce TAFs until after opening time. Also, do ATC take into account the availability of Military / industry airfields in the unlikely situation where there is a major failure and everyone just needs a runway to get onto pronto? I am thinking Brize, Waddington, Hawarden, Warton, Lossiemouth etc.

These minimum fuel rules only work when every stakeholder understands them and knows how to apply them.