Rhiannon, I agree that eliminating the Scouring of the Shire, or replacing Glorfindel at the Ford with Arwen, or skipping Tom Bombadil altogether, are significant changes made to the Lord of the Rings novel in their adaptation to film. But not all of those changes are made solely for the reason of watching the time. I think every adaptation of
Lord of the Rings (except ours!) will skip Tom Bombadil. He's silly, and very little that happens during that interlude will matter later. So, sure, you have to get the barrow-sword into Merry's hand, and you have to deal with some Ring-stuff, and there's Frodo's dreams, but...you can probably do all that without the detour through the Old Forest and the Barrow-downs and meeting Tom Bombadil and Goldberry. Swapping out Glorfindel is an adaptation choice with an obvious reason - it's a cool introduction scene and Glorfindel seems to be an awesome character; but we're never going to see him again post-Council of Elrond. So...why not use that introduction scene for a character you want to, you know, introduce? Bakshi chose Legolas, and Peter Jackson chose Arwen. We'll use it as the last hurrah for Glorfindel, a character whom the audience will have known for many seasons by that point, so it will be a fitting exit for him.
In the case of the death of Saruman, yes, the main constraint was time - they allowed themselves 12 minutes for the story from the fall of Barad-dur/Destruction of the Ring to the end credits, and the Scouring wasn't going to fit in that. But the reason they 'only' had 12 minutes was because they determined the audience would expect a relatively quick denouement once the story was wrapped up, and so introducing a 'side quest' at the end would feel like dragging things out. Obviously, there are people who felt Tolkien dragged out the ending of his book, too, but the point is that that choice was made to 'save time', but also to streamline the ending of the movie and focus on the most important characters (not Saruman). One could argue that the 'change' here was not killing Saruman in Isengard, but rather replacing the Scouring with a return to a peaceful Shire where the adventuring hobbits were now out of place. Meaning, summing up the entire point of that side story in a single image:
Now, whether or not that image is poignant or well done or a valid replacement for the Scouring is a matter of opinion, but it's an adaptation choice.
We, too, must make adaptation choices. And those choices are
meant to be about breathing life into a story and making it as hard-hitting and poignant and meaningful as we all know the
Silmarillion to be, while keeping true to the themes and characters that Tolkien developed. We made a decision long ago not to limit ourselves simply to additions to the story. We have made changes, intentionally, and with reasons. Obviously, not everyone has been a huge fan of the deviations from the text that we've made, but we will continue to deviate. That is going to happen.
The long and short of it is that Tolkien killed Angrod in battle, and his 'significant' actions in the story were getting in a fight with Caranthir, spilling the beans of the Kinslaying to Thingol, and defending Dorthonion. We have him doing all of those things. We've at no point suggested that he not be himself. What
has been suggested is an alteration to the timeline. It's hardly the only timeline alteration in Season 4, nor even the most significant one. I would say that honor probably falls on Finrod requesting Thingol's aid with the construction of Nargothrond
after Thingol knows about the Kinslaying, rather than before. That is a shift in the timeline that profoundly alters the significance/meaning of an event. Not necessarily in a bad way or anything, but clearly the motivations there are not what Tolkien wrote. We've also made some location changes - the Mereth Aderthad is at Vinyamar rather than the Pools of Ivrin, and the Dagor Aglareb is at Minas Tirith and the Fens of Serech rather than Dorthonion. There were reasons for these alterations. Again, we might not all like those reasons, but we did make the changes.
At the end of the day, I am not going to say that I think killing Angrod at the Dagor Aglareb is a necessary change to make. I don't believe it is. But I also don't think it's a disastrous change that will have far-reaching consequences and make it difficult for us to tell the story we need to tell later. It's...simply not that big of a deal.
So, if you want to save Angrod and have him survive Season 4 and (most of) Season 5, then I suggest you write a scene where Gothmog kills Edhellos in the Dagor Aglareb, while Angrod and Aegnor witness this but live. Angrod has been granted a conditional reprieve. It's up to you to make use of it.