To me, solitude suggests rest and contemplation, and an opportunity to spend time in a safe, calm place where I can think about the meaning of life or simply enjoy the natural world. Solitude enables me to consolidate what I have learnt over the day, to reflect upon what is and isn't important.
I think that this is more or less true for most people, and because this means that we are able to make up our own minds, it may be one of the reasons that solitude is being increasingly impinged upon.
When people are deprived of time to themselves to reflect, or to rest, I believe that their critical faculties are impaired. This means that they are more susceptible to persuasion by others, whether that is by people wanting to sell a product, an idea, or an ideology.
I believe that we need a balance. There is nothing wrong with advertising, or with playing computer games or with hearing about people's ideas or ideologies, even where they challenge (especially when they challenge)our own. But too much of one thing without time to really weigh up the longer term implications of our thinking, is harmful not only for ourselves, but for others with whom we share this world. I personally like to hear about many different ways of thinking; of being; of living. In between I need time to be alone to reflect, to integrate what is good and useful, and to discard what is harmful or destructive. It is not good to manipulate others or to be manipulated through deprivation of contemplation time. Live and let live.