They were respectable enough, and were apparently quite popular in their day. I suspect their inclusion was to fit with the overall theme (200th anniversary of Queen Victoria's birth) and they added a novelty value to the concert, as well as fitting into a historical tradition in the concert format. I wouldn't feel qualified to compare them to Schubert or other masters of the Lieder genre. He had chosen texts by his father for three of the songs, Goethe and Uhland for the other two.