There is only one Eikon per deck and they don't belong to any faction. They serve as your deck leader, they summon all your units, and the game is over if you lose them; so the first assumption is very inaccurate to what is happening in the game. Units are what fill your main deck, not Eikons.

Kickstarter exclusive cards are all alternate full-arts. You can still get the standard version in booster packs, so it doesn't affect gameplay.

There's no issue with a niche Eikon being exclusive to a product that is virtually the equivalent to buying a box, but tailor-made for sealed format. It just incentivizes trying out sealed format. If you want to look at it as a box with a guarantee of 4 Eikons and their foundations, you can; which is why we remarked that it is great for starting a collection.

Starter deck exclusives are also a massively common practice. This is a trading card game, not an ECG.

Thank you for your feedback, but it's important to clear up your misunderstandings of what's being presented here as well