Yes the Fiat side is the reason why the project was created. The Altcoin side was added later because it was relatively easy. That does not mean we should ignore the Altcoin side but I also think that pure crypto trade can be solved in a fully automated and trustless way. We plan to go there as well with APIs making the trade automated (look up blockexplorer and confirm altcoin tx) or even Atomic Swaps. But the practice of Atomic Swaps is not that trivial as it sounds from the theory. I dived into that topic for a few weeks in the early days of Bisq. SegWit solves the malleability issue but not the resource and engineering effort issue (run Bisq with x different Altcoins integrated…). So I am not sure if a pure P2P model like Bisq will be the best way to make Atomic Swaps a reality.
Beside that most trades are in USD and EUR, so that is our main market.
For the Fiat side: A hi-prio improvement I will be working on soon will be the security improvement regarding new fiat traders (see https://forum.bisq.io/t/new-requirement-for-payment-accounts-with-charge-back-risk/2376/65).