It's odd because the text is indeed odd, not because someone questions its legitimacy.
There is a paradigm shift that will take most people quite some time to accept. It goes like this: In the past people used to see the text of the ROC constitution as legitimate points of argument to suppress Taiwan's independence. Essentially, when you do that, you are fantasizing yourself as a self-appointed high priest who gets to apply the "sharia law" in the Chinese holy text to the entire Chinese faith.
The paradigm shift happens when the people of Taiwan holds supreme power to "indirectly "interpret what the text of the Roc constitution means, including what's applicable and what's not applicable to Taiwan, without having have to remove a single word from the text.
Or one could say that the non-applicable parts are deemed illegitimate, and only the legitimate parts are applicable.
Hence the text of the ROC becomes a relic. And no more addendum is to be added to the last page. Nothing is to be removed either. A constitutional order emerges where subsequent changes exist in the form of court rulings, precedents, interpretations, and most importantly, other documents. (for example adoption of proclamations, internal treaties, external treaties, bill of rights etc.)
It is up to the Chinese to clone (or to fork) another version of the ROC text and apply it in say, Hong Kong, Shanghai, or New York Chinatown. But in Taiwan where the the people of Taiwan has ultimate say on everything in Taiwan, the paradigm shift was already created.