If you already want to play Skyrim I see no reason not to get the DG and DB.
Many mods need improved scripting support and DB is actually a far better expansion than BM ever was.
Lul what.
Maybe to the blind, deaf, and stupid.
Honestly, Skyrim feels like the game that should have come after morrowind, but instead they made a disappointing sequel(Oblivion) and then resorted to a bunch of nostalgia tripping for the next one and it's DLC(Remember how much you wanted to see DRAGONS in Daggerfall, well fuck HERE'S TONNES OF THEM. Remember that lore about Skyrim and the throat singing siege engine wielders of the voice basically imprisoned on top of a mountain because their very words form magic so powerful it tears towns asunder, remember these people so very rarely mentioned in the tomes in Morrowind and Daggerfall, you'll find out so much they'll be boring.), to cover the deficiencies in story, gameplay, and aesthetic that had and have still been lost since Daggerfall.
DB has half the content. 1/3 the quality and a poor amount of variety compared to BM. More than that, BM wasn't a radical departure from the typical stories and menageries of Morrowind. It was however a radical departure in terms of visuals and aesthetics from Morrowind. It was something that we hadn't seen before, and focused on a people that hadn't been focused on before. Something that DB didn't manage. BM managed to keep things like the Draugr a mystery because they had to be. To make any kind of sense at least. You don't tell everyone that these are ancient undead servants of dragons, bound so far into servitude that their corruption remains beyond death, you can hint at it, but don't deliberately tell us that. Hell, even Oblivion did the whole Elder Scroll plot point thing better. God damn, I'm just so fucking sick of people saying Skyrim and it's DLC are fucking jesus juice, and to hear it here. Even to hear those people deriding better games in terms of aesthetic, story and intention as being worse than something obviously inferior.
Hell, BM may be the approximate size, of DB, but fuck, if it wasn't a hell of a lot better in terms of story, mythos and just general aesthetics, like almost everything in Morrowind was.