The two sides play nothing alike from the very start. TEC don't need to pump out fleet upgrades right off, Vasari do. Tec have shield regeneration capabilities, Vasari don't. Vasari have mobility upgrades and powerful disabling and planetary bombardment weaponry, TEC don't.
Yes, they both have a basic frigate, a missile frigate(sort of, we're being loose here, a look at the damage types reveals that torpedo frigates are designed for nuking capital ships in particular and vastly more effective at it than missile frigates), a flak frigate, a siege frigate, a carrier, a heavy cruiser, and two supports. The supports aren't anything alike, but they both have two supports.
TEC is a production powerhouse, pumping out units in large numbers with ease, vastly greater ease than Vasari. This is true at the start by virtue of skirmishers being eight fleet points instead of five and being a hell of a lot more expensive, and it is true at the end by virtue of TEC having 8 more logistic points on every planet and a percentage of all expenditures from the opposing sides. The vasari are a side based around mobility. They have abilities to take it away from the enemy, and abilities to improve their own. This is true from the start when they can use marauders to boost their own speeds or evacuators to slow the enemy, and it is most definitely true at the end when they have phase gates connecting every planet and can create temporary points deep in enemy space with an inhibitor immune, fast moving capital ship and mass reducing armor upgrades.
Yes, differences exist and the two races don't play the same. But the basic ships and strategies are still very similar. Yes, capitalships aren't the same. BUT: They still all cost the same and there is still 1 battleship, 1 carrier, 1 support, 1 colonizer and 1 planet bomber for both races. From my limited experience both races need roughly the same amount of resources, the same amount of planets and the same amount of fleetpoints to compete with the other race.
Instead of pointing to more differences in other games, consider what really existed. Starcraft took eight years to balance reasonably close,
Uhm, the last balance patch was either 1.08 or 1.09 and those came out in late 2001 and early 2002 IIRC, since then it was all fixing bugs, adding features, adding bugs and fixing the newly added bugs

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and people still bitch about unbeatable strategies.
people are stupid. Professional gamers play all 3 races, they depend on winning to keep their jobs and their incomes, I'm certain most of them would immediatly pick the strongest race if there was one. And none of the people claiming there was an unbeatable strategy can ever back this up.
Fanboy syndrome is hardly a new creation for Sins, instead of the glorious bullshit Starcraft ideal, I see a terribly clunky interface, three unique sides they ripped off from games workshop with barely any modification, and oodles of patches over several years before it resembled the perfect game balance certain individuals had been claiming was there from the start. That it got those oodles of patches over eight years is the high point of Blizzard. They might not be able to get it right to start with or come up with their own ideas, but they at least keep at it unlike most of the gaming industry.
Interface: 10 years old - enough said.
Ripped off from Games Workshop: Yes, nobody else ever does that. And I'm sure GW wasn't inspired somehow from Starship Trooper, Ender's Game, Alien and other books and movies either but invented it all from scratch ?
Patches: Yes, certainly what keeps their games alive so long.
skirmishers floor cobalts.
even if you compare resource and fleetpoint investment and not plain numbers ?
And then, is there are larger strategic difference between cobalts and skirmishers ?
Sorry, the post is a bit rushed, but I wanted to finish it before leaving the computer.