I wouldn’t say it’s bad. Like taking a big open world game like rdr2, you need fast travel one way or another. Either by train or horse fast travel I can pretty go around the whole map without too much hassle. I don’t think that’s breaking immersion and I would also sometime travel the entire distance by horse when I feel like it. You are absolutely free to say you don’t like fast travel as optional mechanic but taking that away would genuinely make an open world game unplayable for me.
Mindustry is definitely must try if you like factory and tower defense elements. It’s free on itchi io and its available on f droid as well. The steam version is paid but it’s just a way to support the dev so you’re not missing out on any game feature. Has cross platform multiplayer as well with a lot of public servers you can jump in once you understand how to play the game.