Here are my rambly thoughts on the Silmarils, for the Silmarils square on the Feanorian Bingo Cards. I feel I should probably apologise for this. Sorry.
One of the problems I have reading the Silmarillion is grasping the Silmarils themselves. Not just what they look like, their beauty, obviously…
I hope you don’t mind if I weigh in and ramble on a bit about the case of Silmarilli myself.
Concerning Fëanor, as I see it I guess it’s not as much about the Silmarilli per se as it is about Finwë’s demise. I’m not stating that the masterpieces of his craft had no impact or importance to him, that would be ridiculous. But “his father was dearer to him than the Light of Valinor or the peerless works of his hands”, and that includes the Silmarilli as well. The thing that really broke Fëanor here was the murder of his father, who was assassinated so the Noldorin jewels and most importantly the Silmarilli could be swept away from Formenos. The bottom line is, Finwë was slain for the Silmarilli to be stolen, his death was a means to an end and not exactly Morgoth’s main intention. Nonetheless that is what happened, Fëanor knows this so he won’t allow the Black Foe to keep the things his father were murdered for. Even if Fëanor had taken the Silmarilli to the feast with him and Morgoth had killed Finwë to arrest, for example, the Palantíri, Fëanor would still go after him to regain those, not because of the jewels themselves, but to avenge his father’s death and to rip from Morgoth the keeping of the goods Finwë was killed for.
Morgoth always wanted light, or better yet, what light might represent (aka the Imperishable Flame, the Secret Fire, the Light of Ilúvatar) and that’s actually why he was so bent on wanting / desiring / coveting also Varda and Arien. Moreover, he wants it for himself and nobody else, he doesn’t want to share it. So even if he could, as you said, uproot the Trees and take them away… think about it, Telperion and Laurelin bring light to a whole continent, it’s as if they could illuminate the whole of the Americas (South, North and Central). If Morgoth took them with him to Middle-earth, the Trees would still overflow that land with their light, and he would not have that. Therefore, he destroys the world’s source of light and takes away with him the only remnant of it. In a way, during a period, Morgoth owns the only light of Arda and in a sense achieves what he’s been struggling for.
As of Thingol, he’s the only Sinda who’s also a Calaquendë. He’s the only one of that kinfolk who has got to witness the splendor of the Light of the Two Trees, and the story is always emphasizing how strong that is (it is essentially so strong that this aspect divides the Elves in Moriquendi and Calaquendi, and again always stressing that the former are somehow lesser than the latter because of said light). I don’t think it is any wonder why Elwë would want that much power within his grasp. I guess in his mind, with a Silmaril in his possession and an Ainu as his Queen, he believes he would be able to turn Doriath into a little “Valinor” of his own and protect his realm forever.
Elwing is yet a whole other case. I’m one of her defenders and to me what she did was a selfless act of ultimate sacrifice. Basically, as I interpret it, she was willing to not only give away her life, but also to be separated from her children for eternity, to keep safe this thing, this object that has the potential to save the world and everyone who lives in it. I won’t get too much into this topic because the post might get even longer than it already is, so I’m just going to leave this one at that.
Now, pondering whether the Jewels are good or bad, I don’t think it’s too difficult to draw a parallel here. I mean, take knowledge as a practical example. Knowledge is primarily a good thing, do you reckon? If not one of the most important things the human race owns. Nonetheless, it is also quite a powerful feature and whoever has it tend to normally keep knowledge to themselves and, depending on how relevant and “scales-tipping" the knowledge is, you cannot fathom the length some people would (and actually do) go to maintain it hidden away from the masses. I see the same here, the Silmarilli are in fact good. What people would do to keep them or gain them, they’re actions to possess them is what’s bad. It’s a matter of perspective, I guess. When the focus is put on the characters instead of the Jewels, it’s possible to realize that the problem resides with the people involved, and their choices, and their actions based on those choices, leading to the sorrowful consequences that sprout from all of it, not with the Silmarilli.
I could try and get even deeper here, as the importance of the Silmarils is not in the Jewels themselves but in what they contain, the mingled light of the Two Trees: “Yet that crystal was to the Silmarils but as is the body to the Children of Ilúvatar: the house of its inner fire, that is within it and yet in all parts of it, and is its life.” See how the Silmarilli are compared to the Children, and their light to the Children’s fëar? It’s all tied in with the Secret Fire, from which not only life but the very existence of Eä is originated and is owed to. And that, the Flame Imperishable, comes from Ilúvatar alone. So I guess, in some level, the yearn for the Silmarilli (or literally for their light) could conceal an underlying longing for God. But I better not get too philosophical about this subject.
Ok, I’m going to end it here. I am too high to go any further than this as of now.. haha