And the carrot-stick guy is the exchanges, and we ain't got nothing to incentivise these people not to use those exchanges.
There is really no incentive to use use centralized exchanges.
Yes, it's probably easier to use them and there is much bigger volume that is probably automated or fake.
You can't get better incentive than knowing your coins are not sent to some third party man who will track your every step and scan your every move and transaction.
I've got another incentive! Money

If you think about it, buying $100 on such an exchange with 0.0007BTC withdrawal fee (~$15 US) at current market price of $22,485.53 and withdrawing, paying 0.0007BTC in fees means instead of 0.00444730BTC, you get 0.00374730 in your wallet, effectively having paid an outrageous price of $26,685.88 / BTC. That's a markup of 18.5%.
Paying an almost 20% premium for having the convenience of buying BTC on an app instead of downloading and installing Bisq, is not something I'm willing to do to be honest.
Honestly, if throughout multiple years of using centralized exchanges, only once you get an account frozen or closed, once you get coins blacklisted, once your exchange exit scams you, or even if you want to withdraw your funds when you buy Bitcoin - a decentralized exchange will actually be cheaper.
We don't know how the future of decentralized exchanges will look like, but it's totally possible to create some revenue sharing that would create profit for everyone who participate in that dex.
Using something like Lightning or other second layer solution, with improved privacy would be big advantage for me, and you don't have to worry about angry employee stealing your data because he got sacked from with work.
What do you mean with revenue sharing? Something like staking / lending features?
Right now, in the case of Bisq the profit you get for 'participating' is that your order stays online. There's no need and no use for you to keep the application running if you don't try to buy / sell which I think is the simplest and most secure way to do things. Sure, you could incentivize users to run their Bisq nodes to 'host' other people's offers and such, so that it's not mandatory to keep the application running to buy or sell. But I don't think it's a good idea; it would make things unnecessarily complicated and introduce many more failure points.
Integrating Lightning is definitely going to be a big step for Bisq (or other decentralized exchanges), as it will allow to DCA more easily and also to quickly get small amounts of fiat when you need it, without requiring to pay relatively high on-chain fees (since it's multisig and there are Bisq fees and whatnot).
I'd definitely agree that having the peace of mind that there's not a company behind the scenes that can mess things up is a big bonus.