Traditional characters is built on common parts for pronunciation and meaning cues. Simplified removed that so IMO it compresses worse and therefore harder. It's visually less dense, but, so what.

Those cues are there in exactly the same way in most simplified characters.

The cases where simplification has removed those cues are rare enough that the extra complexity of traditional characters is really not worth it.

I've never heard anyone claim that simplified characters are more difficult to learn, and it just seems false to me.