The only forum system that does not support this feature is phpBB...
For example with smf there were already ways to do it 15 years ago.

So for some time I have been thinking of some workaround to have that feature without so much work.

I share my idea about it:

1) All urls go through append_sid(), so I think the best thing would be to massively rename the function to url_generation()

2) The $params parameter support string and array. This way the old code would still work.

3) Gradually add where the url_generation() function is used the new values of params that can be used to make our url configurable.

Example:
if I want to transform

viewtopic.php?t=1&f=1 

In this

/f1-your-first-forum/t1-my-topic-titl

you only need to have the name of the forum and the topic in this url_generation() calls

I think that with an approach like this you could have the feature quickly and it can be gradually improved