sunni - shia

I'm not sure that I "get" the sunni-shia split. I mean, I understand the basics of the original conflict, but I don't see why it should be the source of such animosity and violence in the present day. I can't help but wonder if sunni-shia is really just a cover for a different conflict alltogether, much as the "Troubles" and violence in Northern Ireland weren't really about Catholics and Protestants but instead were about ethnicity and land.

At least, from the sunni side I'm sometimes struck by the extent to which it is possible to have love and respect for Ali (ra) and Ahl al-Bayt (That's why I think the sunni Ahl al-Bayt site is so interesting). We all are supposed to accept the Quran, we all are supposed to follow the sunnah, we all are supposed to love Ahl al-Bayt, including Ali (ra).

Occasionally shias often point out the fact that the sunni hadith collections themselves have many exalted things about his status. (e.g. "I am the city of knowledge, and Ali is the gate" or "You are to me as Aaron was to Moses, except there are no prophets after me"). And those things are true, but the question is just how those hadith are to be understood.

What is even more striking (to me anyway) is the fact that almost all the sunni sufi tariqats (except for the Naqshbandis, and perhaps one other) trace their spiritual lineage (silsila) through Ali. So on the one hand, while accepting the status of all four caliphs, sunnis still can say that Ali had a particularly unique spiritual position. (And in the Naqshbandi tradition, some of the other shii imams appear in the lineage instead.) I've even heard a recording of Nuh Ha Mim Keller saying that Ali was the companion he personally felt the closest to because he saw him (ra) in a dream.

On top of that, even though sunni Islam doesn't have the concept of imam (in the shia sense), the sufis do speak of certain individuals being al-insan al-kamil (perfect/universal men) or qutbs (poles) of the age. And these stations would then necessarily be applied to Ali (by the sufis, at least). So without saying that Ali was robbed of his position by the other companions, it is still possibly to recognize the special spiritual status of Ali.

I feel like I'm rambling... but what I'm trying to say is that if a sunni can say all those things and still be sunni, then where exactly is the disagreement?