yeah, those headlines are awful. i didn't take the time to read the articles, though, so maybe there was a pun in there somewhere to justify the incorrect usage?

in any case, i don't think you're going to see "lesser than". if you're going to see "lesser", then you'll probably see it in almost exactly the same contexts in which you would see the word "best".
for instance:
action X is the lesser of two evils <--> action X is the best of the available options
smith has a lesser reputation than jones <--> smith has the best reputation in the group

there are contexts in which "lesser than" could be conceivably be grammatically correct, but i don't think those contacts are considered acceptable usage, ever.
for instance, i don't see any grammatical reason why we couldn't write
smith's reputation is lesser than jones's reputation
... but we just don't.