Maybe its cruel, but its the only way to advance. The projects weren't designed to fail, were designed to success, but they blew up in pieces. The cosmonauts were very concious that their job was a very dangerous one, and accepted the risks. In these endeavours, we put way too much value to human life and safety, this is about exploring and pushing frontiers, both physical and of knowledge, of course there are going to be fatalities among the way, thats why whe say "it's rocket science" for stuff that is hard to do. But as long as the people involved knows the risks involved and accept them, it's ok. Every death advances knowledge and make the next try safer for the next cosmonaut, and both the cosmonauts, and the scientist working with them, deserve my greatest respect.