Unfortunately common sense doesn't always prevail in these situations. The overriding factor in all of this is the safety on the players, umpires & spectators (when present :rolleyes
) The cricket governing body the ICC have to be mindful in this Health & safety mad world that they do all they can to mitigate the situation. It would only take one serious injury or loss of life & they would be looking at legal claims in the 7 figure range, which they don't want. The cricket ball is hard, ask Notts Luke Fletcher who was out all the game after being struck on the head on his follow through while bowling in a T20 match. I've loss count of the times when I've attended a game & an ambulance has carted someone off, after being hit in the crowd & they at least 70 metres away. Players are hitting the ball harder now & the ball can travel long & fast. I've in grounds all my life & you get used to following the path of the ball but sometimes you don't pick it up at all, or lose sight of it at the last minute, that's the time to duck, cover your face & hope for the best.
The general consensus among the media & fans is that they are seen to be consistent in their decisions. In this case everyone including both sets of players looked surprised on the evening of day one when the umpires took them off. It didn't look bad (modern tv cameras enhance the light) but a reading is taken & that is the level that they work to for the rest of the match. I don't even know if a standard light level is used across the board or if they just use their judgement.
In some cases umpires take into account who is bowling & will often give the captain the chance to carry on playing if he bowls slow bowlers or spinners, even then as the light deteriorates they will decide that it's to dark for them to to bowl. Again England had no 90 mph bowlers in their side, but they couldn't bowl. had Pakistan been bowling who have 2 bowlers quicker that England's they would have presumably been penalized earlier by being taken out of the attack or off the field.
On the subject of floodlights, cricket differs from most other sports, the lights are only there to enhance the natural light & not replace them. Once the lights have taken over the natural light shadows are created from each individual pylon, usually 4 or more. Shadows of the ball on the pitch can then be mistaken or confused with the real ball pitching, so off-putting & possibly quite dangerous. Also at this point it effectively becomes a night match so the red ball is less visible & a change to a white or pink ball & black sightscreens would be required & the age of the ball taken into account & the possible swapping from ball to ball. I could go on...