I see your point. But we trade security for convenience 24/7/365. We could all have bulletproof glass in our homes, personal security cameras everywhere, backup generators, panic rooms, etc, but we don't, because it's not convenient (and I know the expense is primarily what makes it not convenient, but I think it's still a valid argument).
Providing access to Wikipedia over http to people in third world countries may be worth the risk of someone MITMing the site with propaganda.
The suggestion is only to give some users the option.