What lineage is good for

Rashi comments that Betzalel came from high lineage; he was a grandson of Miriam and a grandson of Chur, a leader of Klal Yisrael. Oholiav, his partner in the Mishkan, was from a very simple stock, from the low class tribe of Dan. This shows that Hashem gives no recognition given to aristocracy. The simple and the great are all the same to Him. We asked the children that if so, why we do seek out the greatest and most distinguished families to serve in the Beis Hamikdash. Is this a contradiction? One suggestion was that Hashem does not seek aristocracy in of itself, however if it will enhance the job at hand then He will choose it. The Beis Hamikdash service is much more impressive (to us mortals) when done by great people, so we choose noblemen. Not really for their lineage, but because the service is enhanced by their standing.