Yes, I live in Texas now. It's history is fascinating, and much more complex than you seem to understand. I'm only saying that to sweepingly lump the "acquisition" of Texas with the Mexican War is off. In fact, it's sort of looking at it backwards. Texas rebelled in 1835-1836, joined the U.S. in 1845 from the status of a free Republic, and the Mexican war was begun and ended in 1846. Texas, then a state, had a lot to do with the U.S. engaging in that war, of course: Antonio Lopez de Santa Anna kept sending troops north of the Rio Grande. The U.S., having accepted Texas into the union, was bound to defend its borders. If the Mexican War was a war of imperialism, then why isn't Mexico a part of the United States? Hell, they took Mexico City.
Texas history is something I'm still studying, as it is all around me, in museums and libraries and private collections. What one gets in the schools is the bare bones of history, no matter the subject -- and it's not always so very accurate in its assessment of the motives behind events. Sure, slave ownership was probably one of the "economic issues," but there were more, many more Mexican-owned slaves than Anglo-owned. Like much of the U.S., Texas was initially sought out for "a new start" by people who weren't "making it" back in their home states from the Anglo point of view. The entire Anglo population of Texas at the time of its rebellion was under 35,000 -- and there were a LOT of women and children in that number. The fact that Antonio Lopez de Santa Anna had overthrown the legitimate Mexican government and established a dictatorship in Mexico would have had more to do with armed rebellion than an issue that might have otherwise been solved in the Mexican courts and legislature.
As for my being patronizing, sorry if you feel that way. I thought we were just trying to thrash out some facts, and I suppose that living next door to another American country makes me more sensitive on a daily basis to their feelings on the matter than others may be.