I think everyone's different.
#1 - MLU - pool birth. Dim lighting, hypnobirthed, prepared a music playlist but told DH not to bother putting it on, didn't have fairy lights but I would have loved them if we had (it was just before the hospital/MLU started promoting it as a "thing" and friends who have given birth there since have said that the hospital now have fairy lights and LED candles in every room for use if desired). To be honest, the dim lighting in the room was enough for me at the time (and I obviously didn't know any different) but if the lights hadn't been dimmable it would have made a huge difference to have been able to change the atmosphere.
#2 - home - pool birth. I set up fairy lights to ensure dim lighting and relaxing surroundings and prepared another music playlist. Hypnobirthed. Baby was born in the daytime in daylight, which I was not happy about because I was looking forward to my beautiful fairy lit space! Yet again, I didn't use the music playlist ("noise" seems to bother me in labour).
#3 - planning another home birth with pool, hypnobirthing, fairy lights and a music playlist (ha)... really hoping I give birth at night this time round so that I can use the fairy lights (which are still up and look beautiful)! I'm realistic about the fact I'll probably not want the music though (third time lucky?), but nice to have the option... 🤣 I know that (provided I give birth at night) I'll very much want the fairy lights/tranquil lighting. One of my favourite relaxation activities is to have a candlelit bath, so it makes sense to me (along with the cocooning feeling of safety and warmth that soft lighting brings)...
In writing this I realise I've been incredibly lucky to have two really positive birth experiences so far. Perhaps if one/both of my births hadn't gone so well I might dismiss the above as "romantic nonsense", however I can really see the value in doing whatever you can to ensure that your surroundings are set up to ensure that you're in the best "headspace" possible. Each person's experience is unique and totally valid for them.
Personally, I can see the logic in the hypnobirthing theory that clinical settings and bright lighting aren't conducive to producing oxytocin or a calm atmosphere in which you can just "get on with it". I remember reading an article that quoted the Yorkshire Shepherdess as saying she gave birth to one of her children on her own in front of the fire and that sounds perfect to me (although, as much as I like the idea of getting on with it on my own, I'm too risk averse in reality, so having a midwife present seems very sensible).