Was is das "lesser?" Less original, thus in that respect, less creative. Also, if the tie-ins are "creative" enough, they don't actually tie-in, which is false advertising.
Bach's Goldbach Variation; Mozart's variations on "Twinkle, Twinkle, Little Star;" Deethoven's Diabelli Variations; Elgar's Enigma Variations; Ravel's orchestration of Mussourgsky's Pictures at an Exhibition; Liszt's piano transcriptions of Schubert; Percy Grainger's arrangement of Country Gardens....the kind of creativity exhibited in variations on a set theme or in rearrangements of a set theme have been known and acknowledge for some time. They are not the most appealing kind of music, not for audiences nor do they constitute the larger part of any musician's work.
Remakes and reboots might be compared to covers, but generally most people regard even singers or groups who do their own (original or special purchased) material more highly than singers or groups who just do someone else's hits.
If this is all about tie-in books, yes, it is true that some tie-in books are better written than wholly original novels. No one said otherwise, or even explicitly said the opposite.
Tie-in books are still less original. In ordinary language that also means less creative. The point was not to diss tie-in books but to complain about the twin problems of a death of original material and false advertising.