I imagine what the OP meant was 'Would someone be so good as to suggest a paraphrase that might improve on this wording?' ;-)
'So they tend to make 'core meanings' [this phrase must have been defined earlier in the piece] seem more important than they really are.' (This is what some teachers might do. What the students might do is believe they are more important than they really are. Use whichever paraphrase fits your meaning.)
These are my reasons:
'to attach importance to something' is usually unnecessarily grandiloquent, and just adds to the 'fog'
the meaning of 'worthy' is unclear without an 'of'; but CM are not 'not worthy of importance', they are 'not worthy of having so much importance attached to them'. Making this clear would make the syntax ridiculously Byzantine
attaching an abstract noun ('importance') to another ('meaning') and then using an adjective to qualify the second abstraction is just asking to be misunderstood.