I have used the Luke 10 defense many times as a papist, defending mysticism & monasticism. It's a familiar argument. The Lord, however, is not physically present as He was back then, and we cannot exactly sit at His feet. His Holy Spirit comes forth into our hearts to enlighten our minds, and there is nowhere to sit. At any rate, what exactly was Mary doing? She was hearing His word - but what was His word? Bind up the wounded, heal the sick, feed the hungry, care for the dying, visit the imprisoned, and rejoice the lonely - in a word, Love. Our Love is not endless meditation or quietude, but a strong "muscular Christianity", if that phrase doesn't excite too many groans.