According to Larry Doyle, who writes for the show, Smithers was originally just a sycophant in love with the boss.
Larry Doyle never made any comment about the character of Smithers. 
mnli hypothesis: Larry Doyle never made any comment about the character of Smithers.  premise: According to Larry Doyle, who writes for the show, Smithers was originally just a sycophant in love with the boss.