Why increase the 1MB size if blocks ... now after Lightning is available?
If use of lightning was already routine, your rhetorical question might have some value. Alas, a lightning usable by end users is still but a pipe dream.
Why increase the 1MB size if blocks became more empty than they are now after Lightning is available?
With average blocks in the 85%+ of capacity range, you've got a pathological interpretation of 'empty'.