You might have an “ideal” setting already in your mind,please remember that weather is on its own schedule.What if you planned your ideal setting and there was a storm (blocking out your view of the mountains at sunset)? Would you be so terribly disappointed that it would “spoil the effect” so to speak,and you would feel cheated?
I know this isn’t the question you asked, but as a function musician I’d pose the same question when booked for a secular wedding, out of concern a couple may be setting themselves up for disappointment. We’ve seen many “idyllic” outdoor weddings end up anything but, and with most of the guests peeved as well as the happy couple a bit deflated.
Can a marquee be on stand-by as a back-up? Couples may pay the full fee for that even if it isn’t used, or have a desperate scramble to get one at short notice at the same time as everyone else in town will want one too. In some locations it mightn’t be possible to have one delivered anyway.
Elderly guests need seating - next thing your dream outdoor setting has chairs everywhere, which have to be lightweight, so they’ll all be plastic or a mismatch of folding camp chairs. Will nicely-dressed guests have to tramp cross-country/over rocky or soft ground/through sand in evening dress? Or stand for long periods with expensive high heels sinking into grass or mud? Or get covered in wet grass clippings from the lawn mowing and rain shower the day before? Is the couple prepared to specify “Dress: mountaineering” on their invitations?
Are there flies? Mosquitoes? Ants that will be up everyone’s trouser legs before the opening prayer? Are you under a flight path? (Nothing like the whole ceremony grinding to a halt for 40 seconds while a plane flies overhead.)
Does the bride want to make “an entrance”? Can she at the site, or will her cars and hence her egress, dress adjustments etc be in full view of the gathered guests?
Some musicians refuse outdoor gigs unless you provide proper shelter, and if you don’t, may reserve the right to pull out on the day - a nearby tree will not do as “cover”. The hint of two spits of rain, and they and their valuable instruments are outta there. Will the sun be right in their faces as it sets? And there’s no power or sound system for mics for a singer or the celebrant. (That’s not a show-stopper but sometimes someone brings a battery-powered PA which, just like plastic chairs, detracts from the wild woods, back-to-nature atmosphere. Or worse, a battery-powered keyboard. IMO a keyboard of any kind is incongruous outdoors.)
Wind messes up guests’ hairdos. Trying to keep a pristine white wedding veil off your makeup and lipstick in wind is tricky. (I worked that out the first and last time I ever wore makeup, even just getting from house to church.) Woodwind players can be bothered by wind and we even had a gig where the violinist’s bow was blowing off the strings. Pegging the music to the stands was a waste of time because the stands kept blowing over, so we had to anchor them with our feet while playing. (That was an extreme case, though, I will admit.

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Lots of these things can be worked around and not everyone is upset by them but let’s just say I’ve seen some glorious disasters.
I suppose where outdoor weddings go wrong is where people want the outdoor setting
and all the indoor trappings. If the couple and their guests dressed in jeans and hiking boots and toasted marshmallows round the fire afterwards, there’d be very few hitches!