That's the trade off every country is making: dangers of the virus Vs long term effects of response to the virus. It's a balancing act. What would you prefer, wanton destruction of everyone's livelihoods in overreaction? Not everyone is lucky enough to have a job that can be done from home, such as us on this site (typically). Every country is trying to avoid shuttering everything.
The quote from Johnson isn't talking about what you're inferring. It was a broad statement of what was going to happen (and it has, across the world): people will still die, in spite of the lockdown. It was a public address, not a policy statement.
It isn't purely the economics: I've had friends and relatives that have had significant effects to their health (including a death) because of being locked in their houses for months.