And exploring KSC biomes is way funnier than making your 100-th of "testing part X at altitude H and speed V", where X, H and V are incompatible in any usefull regular craft. I don't think scouring KSC is that much rewarding, I would be very surpised to see more than 200 collectible science points, wich are way faster achieved with EVA reports around kerbin, mun, minmus and Kerbol. So I don't feel it's unbalanced. Anyway, this is a sandbox game, so if you feel like completing the tech tree in the first kerbin's days, spend hours of making test contract, if you feel bored of the numerous biomes of minmus and the mun, go interplanetary, if you feel making science at ksc is op, just don't do it (or even go for mods like Btsm), but if you like mission reports and easter egg, you surely want to visit the 30 ksc biomes.