Why indoor climbing became so popular?

Indoor climbing is an increasingly popular form of rock climbing performed on artificial structures that attempt to mimic the experience of outdoor rock.
The equipment, the structure of the surfaces and the usage of the equipment makes indoor climbing easier to practice:  it can be more controlled in such a setting, indoor climbing is perhaps a safer and more friendly introduction to the sport.
Therefore, it may not only be practiced by professionals. Many rock gyms are open for birthday parties and youth teams. Some of them are not even considered to be rock gyms but are seeking for smaller climbing surfaces to be integrated to their spaces.
According to a recent research 1,000 people start climbing every day. Many are inspired by a new generation of climbers, the ones pushing the sport beyond its limits, who often train indoors.
Rock climbing, thanks in large part to the modern climbing gym, has suddenly started up the human performance curve toward athletic maturity. Is that a trend? We don’t know. We do know that there’s a buzz about this great activity, and people want lifestyle facilities that are not hardcore climbing gyms or outdoor training.