What feature do you want to see added?

I'd like all light commands such as //setblocklight, //setskylight, //removelight, //fixlightning to be re-added. They were really useful to me and light blocks don't work the same.

Are there any alternatives?

There are light blocks of course, but they can only add light, not remove it. That's why I really want the old light methods.

Anything else?

You can also make a text warning that will say that light blocks are better to use when you run one of these commands.

Given there is no standard but light blocks across clients, versions, and software vendors anymore, it's not feasible to reimplement lighting manipulation commands as on older versions.

Are there any alternatives? I really liked the thing that the light could be removed or decreased,

Not really, the server can decide to relight the chunk at any time. There is no way to make sure that data is really persisted.