That decision is whether we are going to be professional or hobbyist developers.
If we choose to be hobbyist developers then we have no limitations on the games that we make. We never even have to finish our games if we don't want to.
On the other hand if we choose that we want to be professional developers our choices become much more limited. Firstly we need to make sure the games that we plan to create are achievable with the resources we have at our disposal. Secondly we have to earn money from the games that we create. That second factor is the biggest limitation on our creative freedom once we turn pro.
For the hobbyist developer, making money is a nice bonus, but not an essential outcome from writing games. For the professional, the goal of making money has to be baked into every decision from the beginning. The games that we choose to create are not the ones that we most want to make, but the ones with the highest potential for being profitable.
Most professional indie developers will start out as hobbyist developers and turn pro once that have acquired the expertise and experience they need to make the right choices. Another path is to begin as a professional employed developer and then turn indie, retaining that professional mindset. Each route has its advantages and disadvantages although it's almost always better to have professional experience in employment as a software developer before attempting to become a professional indie developer.
The reason that it is better to have spent time as an employed professional is because that the best way to learn a professional approach to development. You will be familiar with making serious estimates about how much time tasks will take. You will learn project management techniques and how to communicate professionally and effectively. These things are hard to pick up if you move directly from hobbyist to professional.
Its worth bearing in mind that just because you work full time at making games, that doesn't automatically make you a professional. Being professional is about earning enough to cover all of your development costs, including your cost of living.