Sure, theres a really good reason IMO.
Your new colony only has one build queue and thus is severely limited in what it can build in a timely fashion. I have a tendancy to carry Planetary Defense Weapons Platforms on transports to drop on newly founded colonies in hotspot areas.
That way, the fledgling colony is:
1) better protected as it instantly has a full complement of ground batteries and
2) is more productive as it can concentrate from the start on building the facilities necessary to become a productive addition to the Empire.
Also, I've modified my data set a bit so that low pop planets (ie freshly colonized ones) actually build quite a bit slower than the hugely populous Homeworlds. This goes even farther to encouraging cargo ship and transport of population and platforms.
Talenn