Let's talk about the race-specific nukes for a moment; I'm of course referring to the eldritch storm, orbital bombardment, and ork bomb.
These are really cool abilities in concept, and sure it can be pretty fun to use on occasion. However, they're extremely unfun to play against. Now I play at a relatively high level, and I only play with a group of friends who are comparable in skill. I don't often play with randoms. Though the 3v3's with friends are pretty fun, we often discuss whether or not the ultimate abilities are good for the game. They come out relatively early, are cheap to use, and can pretty easily wipe armies during big clashes. For this reason, we sometimes make a house-rule NOT to use them.
Yesterday I played a 3v3 that lasted almost two hours. Why? We just kept wiping each other's armies with a combination of nukes and elite abilities. Though it was a crazy game, it was extremely frustrating at the same time. And after two hours, the team that just happened to get the last nuke in won the match. This recurring theme seems to be how 3v3's are usually decided.
Are the ultimate abilities actually making the game more compelling? I would argue absolutely not.
So what should be changed? I think nukes need a starting cost of 4, not 2. These abilities SHOULD be end-game, not mid-game. At the low starting cost of 2, it means they come out early, and can be used repeatedly for the remainder of the game. Seeing an ork bomb or orbital beam occur 4-5 times per match is pretty unfun. It's also pretty unfun for the person using it as well; use a single ability, hope to win the game. Is that interesting gameplay for either side? Absolutely not.
TLDR: Ultimate abilities are not compelling for the game. They can be used too early and too often. The base cost of the ultimates needs to be 4, not 2.