SoaSE took something like 5-6 years to develop. I remember listening to an interview in which the first 1-2 years was something like infrastructure and research (I might not be remembering perfectly though).
Video game development takes time. Especially when you have 15-20 people and no publisher. That leaves a good ~4-6 programmers to do the workload of double or triple the people. The rest is mostly art department, and everyone seems to double dip and not just do one job, but multiple jobs.
Soada started out with an idea to have a hero and commander mode. The commander mode never worked out. It was too ambitious, too hard to balance, and not fun. It was scrapped before it entered any form of beta.
Ironclad eventually mutually split with IGP in 2013. They were interested in self publishing on Steam and did just that. Unfortunately they had to retool the game from the ground up for Steamworks support (Steam friends support, Steam market integration, party/chat sytems etc.)
So yes, Soada has had a few restarts here and there. Not to mention the entire legal action over the Rebellion name issue took place around this time as well.
Ironclad opted to have an Early Access paywall ($5 is a steal) at Steam's recommendation to help get dedicated testers and to do small scale tests with an active, but small player base. There have been many giveaways. . . but unfortunately many of the keys have been compromised by third party key reseller sites. Free to play should hopefully solve all those issues though.
Eventually the assets from the commander system are now being used as part of the game's Quest mechanic. This combined with free heroes (now and future), craftable (and droppable) skins, Twitch integration, voice chat, and an RPG like Hero Gear and attribute system hopefully makes the game stand out from the crowd. It's also known for its unprecedented developer/community interaction, in which player feedback has been incredibly helpful in shaping the game.
I hope this helps alleviate some of your concerns over Soada's development cycle.
You can find more information and help spread the word here.
Edit: I forgot to mention that the $5 gave an Early Access Bundle which included access to the closed beta, a hero skin, a piece of hero gear, and some crafting materials/recipes. This Early Access Bundle will be retired from Steam when free to play hits. I also read that players who were in the beta before f2p hit will get some special recognition in the future.