Because there's no real demand for them as tools, the product selection lacks depth.

Literal

Tool [as-としての] actual-demand [subject-が] nonexistent [because-から] product-assortment [to-に] depth [subject-が] doesn't-emerge.

~としての is the pre-nominal form of ~として (as): 道具としての実需 = 'actual demand for them as tools.' 品揃え (product assortment/selection) is a retail term. 深みが出ない (depth doesn't emerge) uses the same 深み seen in cooking contexts but applied to product range.