You'd be missing the ball for one thing . Bad light is annoying for spectators but batsmen need to be able to see the ball clearly. At all paces but in particular against the quicks.
Slap and dash is fine under lights, test cricket is harder.
The irony is listening to Michael Vaughan saying how ridiculous they didn’t carry on. I don’t recall him refusing the light whenever it was offered. Can’t abide the man, and comments like that don’t help given he is an ex-player and England captain. I thought he was there to comment from the players’ perspective.
I just think that, in this day and age, we should not be losing the number of overs we do in red ball cricket to bad light. Especially not when you consider how expensive it is to go to a Test these days.