SEED isn't awful, it just strives for mediocrity. It has excellent music, some solid mobile suit designs and Yzak and Dearka are a cool enough pair that they should have been the main characters. But the broad strokes of it are just a copy of 0079 without enough care to make the average soldiers on both sides human.
They turned the series into three movies, but the pacing is absolutely awful, so if you're going to give it a try, you'll have to watch the full series, and I'd recommend the original version at that rather than the HD remaster because cropping the video down to 16:9 is fucking dumb.
But at least Destiny's four movie version is actually a well-paced improvement. Still not a great story, but it's not a disaster like SEED's movie trilogy.
But yes, if you want to skip over one thing to get to another, just do it. Between SEED, 00, AGE and Build Fighters, it's not like you've got many good choices left. At least Unicorn is relevant to what you've already watched.
Have you considered taking a break from Gundam to watch something like Macross, Patlabor, L Gaim or Xabungle?