For a power, you want as many expansions as possible to bump up numbers, so having it cheap close in makes sense but does not shackle those who want to go for broke.Thing is, with a bigger range, it can be interesting for both. For powers to take over more systems in their own and bordering space and for those who want long range colonization.
Maybe there should be some limits/limitations, so it isn't just a race to claim all the most interesting far-flung systems in the first week, but they need to be reachable in a reasonable time.
Also, it makes saving up in a prep phase part of things too- so an explorer would come back with billions, sell those billions for a claim and go on out, or that you'd have a stint becoming a cargo monkey and eventual tycoon to fund it all (drawing in other disciplines).