There is really no incentive to use use centralized exchanges.
There's one case, though, in which I justify the use of centralized exchanges: If you're sending (or receiving) a lot of money via a bank account or another financial institution and there is no legal framework for cryptocurrencies in your country.
This is some trouble, because not only do you have to somehow justify the transaction to the bank, but you also have to be aware of some special-arbitrary treatment from the tax office. Using a centralized exchange is probably going to pull you through the former, but I'm not so sure about the latter. Exchanging with Bisq in this case might not be a wise move.
You're saying if I sell 1BTC on Bisq and I suddenly get $20,000 via bank transfer, which on other days doesn't happen too often, the bank is going to ask questions? I mean, you could just reply to those questions honestly and say you bought BTC at a certain earlier point in time and sold it online. I don't think it would be a big issue; it's going to be similar to buying (or selling) another expensive item like a car.
Maybe the only catch would be that - in your words -
'there is no legal framework for cryptocurrencies in your country'. I'm honestly not sure what happens if there is no 'category' for cryptocurrency
at all, but I believe most countries do have
something by now; so of course make sure that you're legally allowed to own a large sum of BTC without telling anyone, if you want to keep it 'hidden', prior to selling it.
If you're in a country that has sales tax (I believe such as LoyceV), and plan to sell it for fiat in the future, make sure to tell them how much BTC you own (denominated in fiat) and you can hold it anonymously (no need to hand public keys or anything like that) and when the day comes that you're selling it on Bisq, there shouldn't be any issues.
In general I don't think using a centralized exchange to do something illegal in your country, is going to make it legal. If you follow your laws in the first place, you can pretty surely sell P2P without worries.