I'd like to point out that LG infrastructure is identical to regular infrastructure except for that it costs twice as much (and has the added cost of boronide - thanks skoormit for pointing that out). I also believe it *can* be generated as a trade good from other LG colonies, if not the homeworld - so that 1.5b colony should in theory be a reliable source. The only thing the change does is make it so that regular colonies and low-grav colonies can share some infrastructure, with the stated caveat that the low-grav will need twice as much. Oh - I suppose also cargo requirements would change, needing twice as many shipments of regular infra than low grav infra. So, in terms of colonial deliveries, this is actually an *increase* in cost, if you factor in fuel requirements, for the tradeoff of allowing universal use of regular infrastructure.
It is interesting, I'd say, that gravity is reduced to a binary threshold, rather than a gradual increase in infrastructural requirements. IMO, it'd make more sense to me for gravity to be a factor like hydrosphere or temperature requirements, which scale with the difference in ideal vs. actual values. It's a little weird when there can be a colony with perfect 1.0g and a colony with 1.6g or 0.2g without any mechanical difference between the three.
In terms of gameplay decision - shipping low-grav infrastructure to a colony that requires it isn't a decision. But having to weigh the increased infrastructure cost with all of the *other* competing colonies *is* a decision.