I find it fascinating that Picard doesn’t have rename script collections. Basically all other tools have this as main feature. You don’t name your single files the same way when part of the album, compilation, etc.
Renaming should work the same as scripting - allowing multiple scripts to get called from the UI. Some ad hoc UX would be also nice.
I’ve got to agree. While a few eds do include a naming script many do not. It would be very helpful for new editors and users to see some of the variables. IMHO. 
UX regarding this could also be more efficient. Options “[ ] rename [ ] move [ ] save tags” are used regularly and in different combinations so having to click in menu N times is non RSI or time friendly.
There is a ticket to allow multiple renaming scripts for manual selection (PICARD-524) and also a more generic ticket for allowing multiple settings presets (PICARD-9).
The way this is usually done by now is to make it automatic using the scripting. You can have your script name things differently based on any criteria, e.g. you can choose to have different naming rules for various artist releases, for singles, for videos, for standalone recordings etc.
E.g. the default naming script already makes a slight change by including the artist name in file names if the release has more then one title by using $if(%_multiartist%,%artist% - ,).
A typical use case if having compilations named differently, use something like this:
$if($eq(%compilation%,1),
$noop(Various Artist albums)
...,
$noop(Single Artist Albums)
...
)
Instead of checking for compilations with $eq(%compilation%,1) you can also e.g. check for a specific type, e.g. single with $inmulti(%releasetype%,single) or check for video files with $is_video() and many more.
The way this is usually done by now is to make it automatic using the scripting. You can have your script name things differently based on any criteria, e.g. you can choose to have different naming rules for various artist releases, for singles, for videos, for standalone recordings etc.
This is not how this should be done really. You are not writting web applications in Picard ffs 
My current script is general enough and is PITA to maintain and change. Shorter, ad-hoc friendly scripts that are easy to select and change have no alternative here.
Also, DSL is horrible.
Wow created almost a decade ago
But scripting allows for a lot of flexibility and especially automation. Of course a manual selection can be still useful in certain cases. I think the preferred solution would be currently to have multiple renaming setting to choose from on demand.
Early versions actually had a separate naming script for VA releases. But it was changed to a single script. I was not necessarily a big fan of this change, since different handling of VA releases is pretty common. But in the end it is just one of many cases why you want to have a separate script.
Can you not have separate tagging scripts create variables such as _filename and _filepath based on your different naming criteria, and then just have a simple naming script like:
$if2(%_filepath%,%albumartist%/%album%)/$if2(%_filename%,%title%)
You can then enable (or run via right-click) the desired tagging script to produce the _filename and _filepath variables used for renaming.