Yes, Yoda did not agree with Luke going to Cloud City, but having Yoda with him for the duel with Darth Vader would have been a big advantage to Luke. Maybe Yoda thought it was best to stay in hiding in case Luke was killed and he needed to train Leia, but the problem there is that neither Yoda or Obi-Wan had any way of contacting Leia. It didn't seem like Leia could see the force ghosts in Return of the Jedi, so sending Ben to contact her may not have worked. If Luke had died, Yoda most likely would have soon after died of old age without training anyone else. My guess why Yoda marooned himself on Dagobah and never attempted to become personally involved again is because he felt that he had let the galaxy down. Yoda had experienced so many failures, from bringing in the Clone Troopers, to not detecting Sidious' plot, failing to prevent the slaughter of the Jedi and being personally defeated by Sidious that he now doubted his ability to be any real help. Since all of this happened on his watch, would the Rebel Alliance even give him a warm welcome or would he be hated for having been duped and bringing in the Clone Troopers in the first place? It's interesting that when Leia sent for Obi-Wan's help, Obi-Wan was ready to go, even if there was a good chance he could be killed. Yoda made no offer to help even though this could have been his chance to defeat Vader. Yoda was going to die soon anyway. He had nothing to loose by going with Luke and little to gain by staying in hiding.