Imho, long travel times should be a feature of space games that style themselves as "sims". Because if you take that away, you might as well be playing War Thunder with an extra button to teleport to a different map. And because from a universe-building perspective, the second your universe has people traveling to the next star system in less time than it takes me to commute to work in the morning, goods distribution concerns and economic believability are gone.
The caveat, of course, is that there needs to be a point to the long travel and/or a way to skip/mitigate it.. The latter has been thrown out the window by the premise of multiplayer, meaning that the core tool in simulators to alleviate uninteresting travel time, namely time compression, is gone. So your only option then is to only have it vaguely-longish-but-not-really and giving it a point, and here imho is where ED fails and SC should pay attention. You want to provide a navigation challenge, some degree of mechanical requirements, systems to operate, maintenance to take care of, stuff to do that means flight isn't reduced to point-and-stare. But when the game premise is gravity-defying supercruise and ww2 combat, well, it's tough to give a point to smart navigation in the absence of long-range heat source scanning, hiding behind bodies or by going cold, drifting, trajectory calculation, ECM systems, and long-range weapons. Also, fuel not being a concern.
tl;dr: long-ish travel times could (should) be done well, but ED and potentially SC just don't care much about it and are trapped in arcade navigation/combat models anyhow.