Thank you for your answer.
I agree that a full stop makes no difference at the end of a title (and is not used, as a general rule, at the end of titles, headings or captions).
Conversely, ellipsis has several meanings and will definitely make a difference if present:
I sell a bike, a pair of skis, (slightly weird, is there something missing? And why merging these two items in a single topic?)
I sell a bike, a pair of skis, ... (ok, probably selling all my sports gear, there are plenty of things and I write a single message for everything, that makes sense).
I think there are quite a lot of examples, where ellipsis has an unfinished thought meaning, where a title would completely lost its meaning if ellipsis is absent:
This software is not the most user friendly one, but
This software is not the most user friendly one, but...
To my point of view, it would clearly be an improvement to the actual title prettify settings to allow this specific punctuation.