::1) As I already said above, the same thing could be said to several people, including the "Italians" that, according to your logic, wouldn't exist either; many people in Italy still don't even have Italian as their first language, which was imposed by law both in Italy and in Sardinia, so your point is flawed: not to speak about the "Italian culture" thing, which is quite deatable and could be called into question; how could Sardinians share in common something which is all but "common", given the huge amount of internal cultural differences? Please. 
 ::2) Let's assume, for the sake of the argument, that these more or less contemporary "most important people" (all belonging to the Sardinian bourgeousie and the upper class, which is now Italian just like it was Catalan back when the island was Aragonese property...) you're talking about should prove the "true" nature of Sardinian social identity; even then, one could just states their status as assimilated ethnic group (the alterity of Sardinians from Italians was notorious even to Dante, considered the father of Italian language...), just like the Ainu living in the Japanese island of Hokkaido and our Corsican northern brothers that, by the way, are still here on the list in spite of the fact that one of the most important individuals of theirs, Napoleon, had once been non other than the Emperor of French... What's the meaning of this double standard policy?) 
 ::3) Sardinian-speakers are recognized by law (even if not "de facto") as a linguistic minority (they constitute the largest one in Italy), just like the German-speaking South Tyroleans are.  
 ::4) The source says otherwise, as I already pointed out. As long as you don't prove what you're asserting, it's merely your opinion and, being it totally unexplained, should be treated as such. 
 ::5) That page, strangely enough as you'd say, has just been edited a couple of days ago by some people (actually, it's always the same user), whose activity just resulted in edit war, and probably for political, rather than objective, reasons. I'm afraid that a wikipedia article, editable by anyone at any moment, is not that kind of reliable source you're trying to pass off.