Creating a competent and usable level editor that you can publicly release is a lot of work, and unless you can somehow turn it into a major selling point for the game, you will be hard pressed to afford it. Dev time for games is expensive and if you're hacking together levels using a bunch of disparate tools including some third-party ones it might not really be worth it to make a tool that you can release.
Level editing tools are created to build the levels by the devs. They just don't want to give them to players because they want to sell you additional content.
Talking specifically about the usual suspects but hell, even some indie games are doing it now, in indie games it seems more popular to release a new game entirely which is basically 1.0 with new maps but thankfully there are tons of passion projects that get new content for years and years who really deserve more support.
> Level editing tools are created to build the levels by the devs. They just don't want to give them to players because they want to sell you additional content.
This is probably true as well, but the internet editor map editors use are often very different than what they would offer the community, requiring a lot of polish compared to what's used internally (and we all know that the 20% last polish takes 80% of the time) Although there are some games that offer the very same experience, like what Crysis had (with the CryEngine Editor) and ARMA series.
I don't disagree with your assessment and if anything it really opens the door for someone else to step in and offer these tools because if Skyrim, Minecraft, Gary's mod etc have shown us anything it's that these tools can create vast communities that will keep growing and supporting your work and any future releases.
Just a shame to see so many companies prioritise profits over gameplay / replayability and community these days.
There's a world of difference between making a new map/level and making a new game. The effort required for the former is measured in years, whereas the latter is mostly weeks to months (ignoring open world games where the level spans the whole game universe).
