Being limited to one colony without extra skills makes the first planet you pick more important than it already is. Currently you can set up your first colony early to get the basics going and then look for something else to colonize, maybe even something much better.
Plus the colony items strongly encourage having at least one habitable planet and one planet without an atmosphere.
I don’t know if you live in wonderland or what but limit to one planet effectively mitigates the feel of missing out when you do not fill all the available colony quota.
Finding one okay-ish planet is much easier than finding a “perfect” system.
How is the only planet you pick being more important when you are already tolerating mediocre planets to “get the basics going”? It’s exactly serving the purpose of “get the basics going” and just forget about it.
You’re also making wrong assumptions about colony items: you assume people can find infinite amount of every type, which is totally not true. In reality, by limiting to one planet base, a player can immediately go find a planet that can use whichever item he/she just found and not worry about finding all types of items.
It actually gives player more choices, not less, by eliminating the feel of missing out if they don’t fully utilize all available manageable planet quotas.