score:4
As a rule, no. Virtually all Maldives resorts are self-contained on private islands and allow only guests and staff. For this reason there is also no public transport to any of them, you need to arrange with the resort to pick you up or charter your own boat (very expensive).
That said, hotels do love free advertising, so if you contact them in advance and pitch your plan right to the marketing department ("I'm photographing Top 100 Overwater Villas of the World and would love to include you!"), you might be able to wrangle an invite or even a ride. Obviously this will be much easier if a) you have a track record/portfolio to point to, and b) are actually doing this!
Upvote:3
I'm going to counter jpatokal's answer here. There are resorts in the Maldives which allow 'day pass' visitors to visit the resort, including the over-water villas (though, obviously, not entering them). If you are specifically asking about sailing up to the island, landing and taking photos, then the answer is almost certainly a big fat 'no'!
This is not going to be free (approx. $100 US), but cheaper than paying for the obligatory expensive private transfer and the high nightly fees the villas command.
I have a trip planned to the Maldives where we will be staying on the local island of Maafushi and taking a day trip to Olhuveli. This is not the only resort within striking distance of larger local islands or in the vicinity of MalΓ©.