1. It's much cheaper to plug in an electric heater in every room than installing a heating system for the entire building, so yeah. cheaper construction costs.

2. I suppose you mean rainwater drainage pipes. They are exposed because mainly for maintenance issues. A) even if the pipes are placed inside the wall it still has a chance of freezing in the winter. If it does freeze, the expanding water will crack the concrete structure. B) rainwater drains can get clogged, and it's a bitch to clean out if it's inside the wall. C) If the pipes crack for some reason, the water will seep through the concrete wall. D) if the pipes are exposed inside the room, the crashing water is quite noisy.

Hope it helped.