I would and actively do argue that the need for gender market segmentation is increasingly irrelevant in everything but hygiene products, contraception and (arguably) form-fitting clothing. The definition of gender is "the socially constructed roles, behaviours, activities and attributes that a given society considers appropriate for men and women" [Wikipedia]. The trouble with having two pretty boxes to tick is that history has shown, time and time again, that that structure does not work.
For example, Hijra and Two-Spirit are gender identities found in multiple ethnic and cultural groups dating back to before the eighteenth century. These identities are often considered to be comparable to gender-nonconforming identities, as they do not coincide with Western gender constucts. In addition through the fourteenth century 'a' was a gender neutral pronoun which is still used in some English dialects that are alive today; people not identifying with binary genders is not a new concept whatsoever. Before the early twentieth century, clothing worn by infants and children lacked any sex definition. This shows that gender constructs are ever-evolving and are not genuinely necessary in society.
Furthermore, the very term 'gender market segmentation' implies that gender can be segmented at all and is not in actual fact a spectrum, redefined by every individual. How can the market account for every, single person's gender identity?
A case study of Lego shows Lego's advertising to become more and more gender normative from the founding basis that lego is for all. Lego had been failing to sustainably increase sales since 2003, and thus in 2008 launched a four-year market research project into why Lego had failed to reach a sector of the children's market. Lego Friends was subsequently released in June of 2012 and received significant backlash -amounting to a petition signed by thirty-five thousand people- for enforcing gender stereotypes, yet despite this it was seen to be successful with children nonetheless. To some the sales recorded would entail that Lego friends had been exactly what was needed, but the sales acceleration had begun before 2012. In 2008 Lego earnt 1.6€ billion and in 2010, 2.2€ billion. This proves that the revenue increase had already begun three years prior to the Lego Friends release in 2012. The sales jump seen in 2011-2012 was from 2.5€ billion to 3.1€ billion, however, it may be said that this can be put down to other releases made that same year.
In 2012, Lego released; Lego Friends, Star Wars: Battle of Hoth, a range of firefighter and police equipment lego, Avengers action figures and much more. The most notable children's toy released would definitely be the Team GB sets in wake of the 2012 Olympic Games. Conclusively Lego Friends can not be put down as the reasoning for a sales increase seen in 2012, as there were so many other factors. In addition there was evidently no benefit from enforcing gender norms but the opposite (in light of the petition formed rejecting the Lego Friends sets).
To summarise, gender market segmentation is (and has been) potentially harmful to enforce onto children and also financially unnecessary. With so many ways -that are possibly more profitable- to advertise a product, there is no reason to use the form that has the power to cause harm, furthering gender normativity and the exclusivity of binary genders.