Actually, quite a lot about Tuor is written in the UT. Not as much as for Turin of course, but then Turin's tale is the longest story of all, and is a vastly complicated sorrow.
Remember that the Silmarillion (annals of the First Age) is itself, essentially, a sorrowful tale in its entirety; its main power comes through this. (It is the basis for the world, after all.) The story of the Children of Hurin is a significant part of this. The light, or rather the hope of light, comes in at the end of the Silmarillion -- during the Sil itself (while there are, like Tuor's, some glad tales), there is neccessarily more misery than there is happiness (although the hope of happiness is preserved throughout).
As to my opinion, I would say that (referring the above paragraph) Tuor's tale is about the right length. It gives the First Age's sad chronology a joyful -- but short-lived -- episode of light, which is an essential part of the larger and beautifully hopeful tale of of Earendil. (The theme of hope, in fact, can be said to be the purpose of Tuor's existence.)
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