@Anne1313 Airbnb controversially added this restriction in response to complaints that some hosts were discriminating against guests based on race or other assumptions based on the profile photos. I never agreed with this logic myself - and personally, I think if someone was going to treat me differently based on my appearance I'd much rather have them decline my booking than ruin my stay after I arrive. But despite a huge amount of pushback from hosts, Airbnb has only doubled down on this lousy idea, so I think we're stuck with it for awhile.
That said, I think the profile photo is more useful to hosts at the time of check-in than during a booking request. In the absence of reviews, your best indicator of what kind of guest you're going to get is the quality of their communication. If the initial request leaves you in doubt that they're a suitable fit for your offering, ask follow-up questions to get to know a bit about their plans and expectations.
What I look for there is confirmation that the guest understands what they're getting, seems enthusiastic about it, and is able to communicate clearly and respectfully. You might set the bar differently, depending on what your concerns are, but if those concerns aren't resolved by the correspondence, you should decline.
Side note on making photos visible - if someone had to make a decision about you based on your current profile photo, what assumptions do you think they would make? That you're a Belgian nationalist?🇧🇪🤔