If I take my experience (I struggled with the same thing also) and look back at what might have caused that. I'd say it would be the lack of rhythm experience.

yep, rhythm guitar was a weak point and instead of working on that I started lead. I can now say I stepped into lead way too fast.

This is just a thought but if someone doesn't have a good grasp of rhythm guitar he probably won't be faced with working on different rhythmic pattern.

This is also why I think studying different styles of music, even if you don't play that style ever, opens your mind to new rhythms.

Just out of curiosity Ren, how is your student rhythm guitar?