For the first part of the question, the answer will vary by jurisdiction. Generally, the carrier's flag country's regulations will be the ones that apply.
In the case of U.S. carriers, there is no certification that would allow this on a scheduled passenger airline, per 14 CFR 121.311(e):
Except as provided in paragraphs (e)(1) through (e)(3) of this section, no certificate holder may take off or land an airplane unless each passenger seat back is in the upright position. Each passenger shall comply with instructions given by a crewmember in compliance with this paragraph.
(e)(1) - (e)(3) don't exclude business-class (or any class) seating from this requirement.
Presumably, EASA and/or the UK's CAA have regulations that allow seats to be certified to take off and/or land with seat positions other than upright if such position would not impede evacuation in the event of an emergency.
For the second part of the question, Air New Zealand is another example where this is allowed in business class. With the 1-2-1 seat configuration, a reclined seat in business class is not impeding the evacuation of any other passenger. For example, in this Air New Zealand 777 pre-flight safety video, they say:
We ask that you place your tray table back, your leg rest down, and ensure your seat back is upright, unless you're in Business Premier, where you choose your own seat back position.
As for my personal opinion, if I were writing the regs, I wouldn't allow this. Lying down is simply not a good position to be in if the plane were to skid off the runway or something else happened where you needed to evacuate quickly. And most business class seats (at least all of the ones I've ridden in) are reclined by electric motors, which would not be able to reliably bring them back to the upright position in the event of an emergency, which would make it a bit more difficult for the passenger to evacuate. Most reasonably healthy people could still get out, but would be a bit slower in doing so. Less healthy people, especially the elderly and/or disabled might not be able to get out at all from the reclined position without help.