Keynesian isn't a value judgement on whether various sorts of consumption are good. It's firstly a description of how capitalist economies actually work, and secondarily a toolkit of policy based on that description. The focus on demand is primary because how it affects the economy writ large.

In fact, Keynes himself famously thought that would be working 15 hours a week by now instead of...well...wherever all the work is going, some of which I suppose is propping up the consumption you don't approve of.