These rankings depend on the metrics that USNWR decides are important indicators of academic excellence. Therefore, from the start you have to keep this in mind. The metrics they use may or may not be favorable to A&M (as you mentioned Acceptance Rates may be one of them). I don't know all of the metrics they use or pay attention to USNWR for two reasons:
1. If I want to go to graduate school somewhere, the last thing I would ever do is look up the USNWR rankings. No student wanting a doctorate would ever look at the USNWR grad school rankings and base their decision off them. These students will be more concerned about the specific fields of research that the school offers, and they will also be extremely concerned about possible faculty advisors. Also, if you are wanting to go towards graduate education, you should be looking for advice from your own Professors and not an online ranking service that has known issues with corruption (falsified self reported SAT scores, avg class ranks, acceptance rates, etc.) This thinking also applies for a masters. I would trust A&M faculty opinions way more than those of statisticians crunching numbers with metrics that may be absolutely meaningless to me.
2. If I don't want to go to graduate school, then I am going to be most concerned about my chances of achieving full time employment with a reputable company after I graduate. I also want to know if the school I am considering has a Department of Science/Engineering/Business that will provide me the education necessary to reach this goal. Some people care about student to faculty ratios and other metrics that may assess the quality of education you received, but for me these things are not as meaningful as the employment prospects I will have when I graduate. For my case, I know A&M provides a quality engineering education, and the school also provides extensive opportunities to find employment with top notch companies through career fairs and the career center. For my case, SMU being ranked higher than A&M means absolutely nothing because their engineering program is extremely young and is not even in the same league as A&M.
TL;DR version: I would be cautious about using USNWR rankings as the ultimate authority on University prestige. I would also warn prospective students to be cautious about basing their decisions off these rankings unless they truly understand, agree with, and highly value the metrics used in the study.