Contractions that are avoidable would be advantageous in certain cases.
For Simple English rendering, we might have a rule that says *no
contractions* would be allowed. This would help others learning a language
or simply having smart auto-completion as you type on a Wikipedia page for
instance to replace "we'll" with "we will" as an example. Or a
rendering for those that might have their Wikipedia Babel native language
for English set to en-N, then you might *want contractions* in order to
avoid verbosity for those that could quickly read and understand English
sentences that have them.
In general, there are tons of use cases for renderers that I have thought
of and this is only 1 of them, but they all rely on constructors,
functions, and lexicographical data stored well and in some standardized
fashion somewhere. Which is why I am always asking about best practices
within Wikidata's Lexeme namespace. I find that I often look for some of
the most complex issues to deal with which helps make it easier for me to
understand where the gaps will likely be in any system. Then we can begin
conversations on how we'll tackle them.
Looking forward to others' opinions!