I agree with you. Fast travel is extremely useful, and I think that there is a better solution to exploration than nerfing all travel. But I personally don't think that your suggestions address the problem either. They would increase exploration, but only in and around the town areas, which would be explored anyway with fast travel. The problem is not that important areas don't get explored, but that everything in between that has been meticulously crafted it rarely explored.
Although I disagree with the decision to make travel so difficult, I believe that it will be fine. The Minecraft server Wynncraft has travel similar to that of the Revelis Update: a few abilities that give extra mobility (volo, appareo, ascendio), teleport scrolls (warpkeys/firedust) that can be bought in each town for a fairly high price, and horses that are difficult to get and barred at a certain level (brooms). It may seem like its terrible because travel is difficult, but it's actually very manageable. Even though it has an extremely large map (probably bigger than the new world map) and it takes a very long time to cross, you almost never find yourself having to travel across the whole map. Occasionally it gets boring to run across the map to get to an important area, but even then there's still plenty to find. It's actually a really fun map to explore because when I'm just trying to rush my way to a quest I might find a secret area or new monsters to fight. If I could teleport anywhere I wanted for virtually free, it wouldn't be as interesting.
That is what I think Potterworld travel will end up being like: slower, but more interesting and immersive. And although I have some problems with it (most notably fire dust being so expensive), I think that overall it will be a positive change.